首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   1809篇
  免费   201篇
  国内免费   30篇
耳鼻咽喉   7篇
儿科学   49篇
妇产科学   103篇
基础医学   266篇
口腔科学   17篇
临床医学   154篇
内科学   397篇
皮肤病学   14篇
神经病学   140篇
特种医学   163篇
外科学   208篇
综合类   45篇
一般理论   1篇
预防医学   62篇
眼科学   31篇
药学   152篇
中国医学   14篇
肿瘤学   217篇
  2023年   8篇
  2022年   16篇
  2021年   27篇
  2020年   22篇
  2019年   28篇
  2018年   37篇
  2017年   36篇
  2016年   27篇
  2015年   52篇
  2014年   62篇
  2013年   75篇
  2012年   127篇
  2011年   123篇
  2010年   90篇
  2009年   82篇
  2008年   104篇
  2007年   97篇
  2006年   83篇
  2005年   90篇
  2004年   96篇
  2003年   79篇
  2002年   73篇
  2001年   60篇
  2000年   63篇
  1999年   65篇
  1998年   14篇
  1997年   22篇
  1996年   25篇
  1995年   18篇
  1994年   11篇
  1993年   11篇
  1992年   30篇
  1991年   28篇
  1990年   33篇
  1989年   25篇
  1988年   24篇
  1987年   25篇
  1986年   18篇
  1985年   17篇
  1984年   17篇
  1983年   13篇
  1982年   10篇
  1981年   11篇
  1980年   7篇
  1979年   13篇
  1978年   9篇
  1977年   9篇
  1976年   7篇
  1972年   4篇
  1971年   4篇
排序方式: 共有2040条查询结果,搜索用时 18 毫秒
71.

Purpose

Shunt procedures used to treat cryptococcal meningitis complicated with hydrocephalus and/or increased intracranial pressure (IICP) could result in cerebrospinal fluid (CSF) overdrainage, thereby presenting therapeutic challenges.

Methods

We analyzed the clinical features and neuroimaging findings after the ventriculoperitoneal (VP) shunt procedure in 51 HIV (Human Immunodeficiency Virus)-negative patients with cryptococcal meningitis, to assess the risk factors associated with post-shunt CSF overdrainage.

Results

Symptomatic CSF overdrainage occurred in 12% (6/51) of patients with cryptococcal meningitis who underwent the shunt procedure. Rapid deterioration of neurological conditions was found in 6 patients after the shunt procedure was performed, including disturbed consciousness, quadriparesis, and dysphasia in 5 patients and severe ataxia in 1. The mean duration of CSF overdrainage after the shunting procedure was 2–7 days (mean 4 days). The mean interval between meningitis onset to shunting procedure remained independently associated with CSF overdrainage, and the cut-off value for predicting CSF overdrainage in interval between meningitis onset to shunting procedure was 67.5 days.

Conclusions

CSF overdrainage after the VP shunt procedure is not rare, especially in patients with a high-risk of cryptococcal meningitis who also have a prolonged duration of hydrocephalus and/or IICP.  相似文献   
72.
Purpose: Aldehyde dehydrogenase 1A1 (ALDH1A1) has been proposed as a candidate biomarker for colorectal carcinoma (CRC). However, the heterogeneity of its expression makes it difficult to predict the outcome of CRC. The aim of this study was to evaluate the diagnostic and prognostic value of this molecule in CRC. Methods and Results: In this study, we examined ALDH1A1 expression by immunohistochemistry including 406 cases of primary CRC with corresponding adjacent mucosa, with confirmation of real-time PCR and Western blotting. We found that the expression patterns of ALDH1A1 were heterogeneous in the CRC and corresponding adjacent tissues. We defined the ratio of ALDH1A1 level in adjacent mucosa to that in tumor tissues as RA/C and found that the capabilities of tumor invasion and metastasis in the tumors with RA/C < 1 were significantly higher than those with RA/C ≥ 1. Follow-up data showed the worse prognoses in the CRC patients with RA/C < 1. For understanding the underlying mechanism, the localization of β-catenin was detected in the CRC tissues with different patterns of ALDH1A1 expression from 221 patients and β-catenin was found preferentially expressed in cell nuclei of the tumors with RA/C < 1 and ALDH1A1high expression of HT29 cell line, indicating that nuclear translocation of β-catenin might contribute to the increased potentials of invasion and metastasis. Conclusion: Our results indicate that RA/C is a novel biomarker to reflect the distinct expression patterns of ALDH1A1 for predicting metastasis and prognosis of CRC.  相似文献   
73.
We report a rare case of early-stage endometrial adenocarcinoma in a 22 year old nullipara with polycystic ovaries undergoing conservative treatment. Pretreatment evaluation including tumour grade, depth of myometrial invasion, tumour size, hormone receptor status and flow cytometric analysis indicated a favourable prognosis. The patient underwent repeat endometrial curettage and a 6 month period of therapy with megestrol acetate and tamoxifen. A combination contraceptive pill was then prescribed to ensure withdrawal of the menstrual cycle thereafter. Now, 1 year after the last curettage, there is no evidence of disease. During the treatment period, hysteroscopy allowed for a more precise approach in panoramically examining the tumour nest in the endometrial cavity, and the subsequent endometrial response to hormone therapy. Laparoscopy using bulldog clamps applied to the isthmic portion of the Fallopian tubes prevented i.p. spread of endometrial tissue from retrograde regurgitation during hysteroscopy. Laparoscopic ovarian electrocautery resulted in the reduction of abnormal hypervascularization on the surface of polycystic ovaries postoperatively but caused a peri-ovarian adhesion complication. It is interesting that this case posed a unique opportunity to demonstrate the tumour regression under the assistance of laparoscopy and hysteroscopy.   相似文献   
74.
We sought to investigate the anti-severe acute respiratory syndrome (SARS)-associated coronavirus (SCoV) activities of type I (alpha and beta) and type II (gamma) interferons (IFN) in vitro. Type I IFNs protected cells from cytopathic effects (CPE) induced by SCoV, and inhibited viral genomic RNA replication in FRhk-4 cells (measured by quantitative RT-PCR) in a dose-dependent manner. Intracellular viral RNA copies were reduced 50% by IFN-alpha at a concentration of 25 U/ml and by IFN-beta at a concentration of 14 U/ml. IFN-gamma had fewer effects on inhibition of viral infection and replication. The type I IFN receptor signaling pathway in host cells is mainly involved in the inhibition of SCoV infection and replication. Type I IFNs could be used as potential agents for anti-SARS treatment.  相似文献   
75.
Kung JH  Zygmanski P  Choi N  Chen GT 《Medical physics》2003,30(6):1103-1109
The motion of lung tumors from respiration has been reported in the literature to be as large as 1-2 cm. This motion requires an additional margin between the Clinical Target Volume (CTV) and the Planning Target Volume (PTV). In Intensity Modulated Radiotherapy (IMRT), while such a margin is necessary, the margin may not be sufficient to avoid unintended high and low dose regions to the interior on moving CTV. Gated treatment has been proposed to improve normal tissues sparing as well as to ensure accurate dose coverage of the tumor volume. The following questions have not been addressed in the literature: (a) what is the dose error to a target volume without a gated IMRT treatment? (b) What is an acceptable gating window for such a treatment. In this study, we address these questions by proposing a novel technique for calculating the three-dimensional (3-D) dose error that would result if a lung IMRT plan were delivered without a gated linac beam. The method is also generalized for gated treatment with an arbitrary triggering window. IMRT plans for three patients with lung tumors were studied. The treatment plans were generated with HELIOS for delivery with 6 MV on a CL2100 Varian linear accelerator with a 26 pair MLC. A CTV to PTV margin of 1 cm was used. An IMRT planning system searches for an optimized fluence map phi(x,y) for each port, which is then converted into a dynamic MLC file (DMLC). The DMLC file contains information about MLC subfield shapes and the fractional Monitor Units (MUs) to be delivered for each subfield. With a lung tumor, a CTV that executes a quasiperiodic motion z(t) does not receive phi(x,y), but rather an Effective Incident Fluence EIF(x,y). We numerically evaluate the EIF(x,y) from a given DMLC file by a coordinate transformation to the Target's Eye View (TEV). In the TEV coordinate system, the CTV itself is stationary, and the MLC is seen to execute a motion -z(t) that is superimposed on the DMLC motion. The resulting EIF(x,y) is input back into the dose calculation engine to estimate the 3-D dose to a moving CTV. In this study, we model respiratory motion as a sinusoidal function with an amplitude of 10 mm in the superior-inferior direction, a period of 5 s, and an initial phase of zero.  相似文献   
76.
The conventional method for impressions of flabby tissue uses modified trays and highly flowable materials, but mucostatic impressions are difficult to achieve due to the viscous and the elastic natures of impression materials. In this report, a technique is presented in which conventional impression and intraoral scanning for a fully edentulous patient with flabby tissue are combined. The definitive impression was obtained by applying appropriate pressure to each tissue area, and the denture can be maintained passively and stable at rest and during function.  相似文献   
77.
Cutaneous T cell lymphoma: characterization by monoclonal antibodies   总被引:10,自引:0,他引:10  
Kung  PC; Berger  CL; Goldstein  G; LoGerfo  P; Edelson  RL 《Blood》1981,57(2):261-266
Monoclonal antibodies to human T cells permit the characterization of the surface phenotype of cutaneous T cell lymphoma (CTCL). The majority of CTCL cells are reactive with OKT1 and OKT3 monoclonals, which identify peripheral T cells and mature thymocytes. The neoplastic cells also react with OKT4, which recognizes the inducer T cell subset; they are, however, unreactive with OKT5 monoclonal, which identifies cytotoxic/suppressor T cell subsets. These data are in agreement with previous functional studies demonstrating that CTCL is a neoplasm of inducer (helper) T cells.  相似文献   
78.
ObjectiveTo evaluate the impact of the duration of cryopreservation of testicular sperm on clinical and neonatal outcomes after intracytoplasmic sperm injection (ICSI) for patients experiencing azoospermia.Materials and methodsThis study included 132 azoospermic men who participated in 212 ICSI cycles. The participating men underwent testicular biopsy for the cryopreservation of tissue to be used for subsequent ICSI cycles. The duration of the storage of testicular sperm was determined by the time of oocyte retrieval. Fertilization, embryo development in vitro, pregnancy rates, and neonatal outcomes were assessed.ResultsAlthough the mean percentage of viability decreased from 73.2% prior to freezing to 50.2% after thawing, viable spermatozoa were visualized subsequent to thawing of the tissue samples for all patients. The potential for fertilization and subsequent embryonic development was not influenced by the duration of sperm cryopreservation up to 2 years longer. The pregnancy outcomes also varied independently of the duration of sperm cryopreservation. The duration of storage did not appear to affect the neonatal outcomes adversely, including the Apgar score and intensive care unit admission rates, although neonatal outcomes were influenced by advanced maternal age. It also has no obvious impact on the major and minor congenital malformation rate of the newborns.ConclusionICSI outcomes, pregnancy outcome, neonatal outcome, and congenital malformation rate appear not to be affected by the duration of the period of cryostorage. An earlier start of the ICSI cycle following the testicular sperm cryopreservation is preferable because longer preservation is associated with more advanced maternal age.  相似文献   
79.
ObjectiveThe purpose of this study was to evaluate the efficacy and feasibility of concomitant trocar-guided transvaginal mesh (TVM) surgery with a midurethral sling (MUS) for treating women with advanced pelvic organ prolapse (POP) and stress urinary incontinence (SUI) or occult SUI (OSUI).Materials and methodsEighty-nine women with advanced POP and SUI or OSUI were retrospectively enrolled. The Total Prolift and Tension-free Vaginal Tape-Obturator Systems were used for trocar-guided TVM surgery and MUS. Patients received regular follow-up at 1 week, and 1 month, 3 months, 6 months, and 12 months postoperatively, and then annually thereafter. The endpoints were the success rate for POP, and perioperative and postoperative complications. Functional outcomes were the presence of voiding difficulty, persistent or de novo overactive bladder symptoms, postoperative SUI, and paresthesia.ResultsThe median follow-up period was 35 months (range, 12–50 months). Within the follow-up period, 84 patients (94.4%) were objectively cured, five patients (5.6%) had vaginal apical mesh exposure, 29 individuals (32.6%) had persistent or de novo overactive bladder symptoms, six individuals (22.5%) had de novo SUI (two were found by urodynamics), and nine individuals (10.1%) had voiding difficulties (two were found by urodynamics). In addition, the vaginal hysterectomy group had greater blood loss, longer operation times, and a higher mesh erosion rate compared to the uterine suspension group.ConclusionConcomitant trocar-guided TVM surgery and MUS with the use of total Prolift and Tension-free Vaginal Tape-Obturator offer good efficacy in treating women with advanced POP and SUI or OSUI. The vaginal hysterectomy group had more perioperative complications.  相似文献   
80.
ObjectiveTo compare medical costs of three surgical procedures for the treatment of primary stress urinary incontinence: the laparoscopic Burch colposuspension procedure, the laparoscopic two-team sling procedure, and the transobturator tape (TOT) procedure.MethodsWe performed a retrospective observational study of isolated minimally invasive surgical procedures (no concomitant surgery) in 18 women with primary stress incontinence. Six women underwent a laparoscopic Burch colposuspension procedure, six underwent a laparoscopic two-team sling, and six underwent a TOT procedure. The main outcome measure was the mean aggregated medical cost per patient treated. Itemized calculations were made for (1) equipment costs; (2) surgeon, surgical assistant, and anaesthesiologist reimbursements; (3) nursing costs; (4) operating and recovery room costs; and (5) costs of stay in hospital.ResultsThe mean cost per patient undergoing a TOT procedure was $2547 (95% CI $2260 to $2833); for a laparoscopic Burch colposuspension it was $4354 (95% CI $3465 to $5244); and for a laparoscopic two-team sling procedure it was $5393 (95% CI $4959 to $5826). Significant differences were found across procedures using a one-way ANOVA. A TOT was lower in cost than both a Burch procedure, with a mean cost difference of $1807 88 (P < 0 001), and a sling procedure, with a mean cost difference of $2834.73 (P < 0.001).ConclusionA transobturator tape procedure has less direct medical costs than a laparoscopic Burch colposuspension or a laparoscopic two-team sling procedure in the surgical treatment of stress urinary incontinence.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号