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   4555篇
  免费   164篇
  国内免费   23篇
耳鼻咽喉   63篇
儿科学   113篇
妇产科学   25篇
基础医学   624篇
口腔科学   207篇
临床医学   260篇
内科学   1047篇
皮肤病学   64篇
神经病学   352篇
特种医学   202篇
外科学   694篇
综合类   18篇
预防医学   177篇
眼科学   106篇
药学   349篇
中国医学   3篇
肿瘤学   438篇
  2023年   40篇
  2022年   38篇
  2021年   107篇
  2020年   67篇
  2019年   96篇
  2018年   86篇
  2017年   98篇
  2016年   95篇
  2015年   102篇
  2014年   127篇
  2013年   144篇
  2012年   291篇
  2011年   295篇
  2010年   140篇
  2009年   149篇
  2008年   301篇
  2007年   298篇
  2006年   290篇
  2005年   311篇
  2004年   323篇
  2003年   240篇
  2002年   290篇
  2001年   54篇
  2000年   54篇
  1999年   64篇
  1998年   69篇
  1997年   62篇
  1996年   38篇
  1995年   51篇
  1994年   39篇
  1993年   44篇
  1992年   38篇
  1991年   22篇
  1990年   33篇
  1989年   18篇
  1988年   21篇
  1987年   15篇
  1986年   12篇
  1985年   11篇
  1984年   15篇
  1983年   15篇
  1982年   16篇
  1981年   17篇
  1980年   17篇
  1979年   16篇
  1978年   17篇
  1977年   10篇
  1971年   4篇
  1968年   7篇
  1967年   5篇
排序方式: 共有4742条查询结果,搜索用时 153 毫秒
21.
The patient was a 48-year-old male who was diagnosed with unstable angina. He had worsening cardiogenic shock during coronary angiography. Emergency coronary artery bypass grafting (CABG) was performed. He had a methicillin-resistant Staphylococcus aureus (MRSA) mediastinitis on day 22 after CABG. Drains were placed in the anterior mediastinum, left thoracic cavity, and abscess cavity, and another drain was placed in the mediastinal space for continuous cleansing with povidone iodine, oxydol. For antibiotics, teicoplanin (TEIC) was administered intravenously and to the local site via the cleansing drain for about one month. No MRSA was detected by culture in discharges from the mediastinal drain. Inflammatory findings were improved, and the patient was discharged and resumed everyday life without recurrence of inflammation as of eight months. Although the number of cases of MRSA mediastinitis is small and accumulation of cases is necessary to investigate therapeutic methods and selection of antibiotics, our department will select closed continuous cleansing and TEIC for antibiotics as the first choice for MRSA mediastinitis, and accumulate cases to investigate its efficacy.  相似文献   
22.
Two flat adenomas and a flat mucosal carcinoma of the colon were reported in patients with synchronous and metachronous colonic carcinomas. These lesions were almost flat and were not detected by preoperative endoscopic examinations. Colonoscopists should be aware of the presence of flat adenomas, which can be easily missed, and recognize them as lesions that play an important role in the "adenoma-carcinoma sequence."  相似文献   
23.
CA 125 is an antigen associated with non-mucinous epithelial ovarian cancer, which is defined by OC 125 antibody developed by immunizing ovarian cancer cells. We have produced two monoclonal antibodies, 130-22 and 145-9, by using the human lung adenocarcinoma cell line PC-9. Both 130-22 and 145-9 antibodies recognized CA 125 antigen. However, the binding sites seemed to be separate from those of OC 125. Testing by 9 immunoradiometric assays (IRMA), using different combinations of the 3 monoclonal antibodies 130-22, 145-9 and OC 125 demonstrated that the best standard curve for detecting CA 125 could be obtained by a "simultaneous sandwich" assay based on a mixture of 125I-labeled OC 125 and 130-22 or 145-9 coated beads. One-step IRMA, using 130-22 as a tracer and 145-9 as an immunoadsorbent, also showed good reproducibility and sensitivity for measuring CA 125. Antigens were detectable in the culture supernatants of PC-9 cells and 5 of 6 ovarian cancer and endometrial adenocarcinoma cells. These results indicate that one-step IRMA using 130-22 and 145-9 is useful for detecting CA 125 antigen.  相似文献   
24.
Summary: The polycondensation of 1‐ethynyl‐2,5‐dihexyl‐4‐iodobenzene in the presence of 1‐ethynyl‐2,5‐dihexyl‐4‐(2‐phenylethynyl)benzene proceeds according to the mechanism of initiated chain growth polycondensation. It has allowed the synthesis of oligomers with a desired molecular weight and a narrow molecular weight distribution. The reasons for the side reaction leading to the formation of diyne compounds are revealed and the presumed mechanism is given. This opens prospects for the preparation of defectless poly(p‐phenyleneethynylene)s with required molecular weights and narrow molecular weight distributions.

  相似文献   

25.
The histogenesis of malignant fibrous hlstlocytoma (MFH) was studled using clsplatln (CDDP)-resistant MT-R8 and MT-R9 cells derlved from cloned undlfferentiated MT-8 and flbrohlstlocytic MT-9 cells, resoecthfely, which had been established from transplantable rat MFH. CDDP concentrations requlred for 50% suppression of prollferation of MT-R8 and MT-R9 cells were 5.4– and 3.3-fold greater than those of parental MT-8 and MT-9, respectively. MT-R8 and MT-Rg showed the higher positive rates to histimytic lysosomal/ antigenic (ED1 and ED2) markers. The number of a-smoath muscle actin (SMA)-positive cells significantly Increased in MT-RB; SMA-positlve cells were also obsenred in MT-R9, but no difference was seen between MT-9 and MT-R9. MT-R8 and MT-R9 expressed both histiwytic and myofibroblastic phenotypes. However, the histology of subcutaneous tumors induced in syngeneic rats by MT-R8 and MR-R9 did not always reflect their in vitro nature. MT-R8 developed undiffer-entlated sarcomas similar to parental MT-8 tumors. In contrast, MT-R9 induced tumors with polytypic histologies such as the storiform growth pattern, neoplastlc growth of granular cells and myofibroblasts, osteosarcoma-like areas, collagen-rich areas containing well-developed fibroblasts and areas involvlng many lipoblasts. These In vivo observatfons suggest the multidlrectional differentiation of MT-R9 cells. Phenotypic modulation of rat MFH cells seemed to be easily induced by CDDP. A possible histogenesis of MFH was discussed based on the data collected.  相似文献   
26.
The film surface of poly(gamma-benzyl-L-glutamate) (PBLG) was modified with 2-aminoethanol to enhance its hydrophilicity. Controlling the reaction conditions of PBLG and 2-aminoethanol, various types of copoly(gamma-benzyl-L-glutamate, gamma-hydroxyethyl-L-glutamine) film surfaces were obtained. Surface free energy (gamma sv), the dispersive component of gamma sv (gamma dsv), the nondispersive component of gamma sv (gamma psv), and the interfacial free energy of polymer surface with water (gamma sw), which were obtained by using the contact angle measurement and calculation method proposed by Andrade et al., were changed remarkably by the aminolysis. The gamma sv value increased after 2 h of aminolysis from 48.2 (PBLG) to 65.3 dyn/cm and gradually increased to around 70 dyn/cm after 12 h reaction. (gamma dsv) and (gamma psv) changed from 31.0 and 17.2 dyn/cm (PBLG) to 26.5 and 44.3 dyn/cm, respectively. These parameters of the material surfaces, modified over 12 h reaction, were found to be similar to those of the surfaces of canine aorta, vein, and human fibrin membrane. Blood clotting times on these polymer surfaces were comparatively longer than on siliconized glass surfaces.  相似文献   
27.
We tested the hypothesis that arterial baroreflex (ABR)-mediated beat-to-beat control over muscle sympathetic nerve activity (MSNA) is progressively modulated as orthostatic stress increases in humans, but that this control becomes impaired just before the onset of orthostatic syncope. In 17 healthy subjects, the ABR control over MSNA (burst incidence, burst strength and total MSNA) was evaluated by analysing the relationship between beat-to-beat spontaneous variations in diastolic blood pressure (DAP) and MSNA during supine rest (control) and during progressive, stepwise increases in lower body negative pressure (LBNP) that were incremented by −10 mmHg every 5 min until presyncope (nine subjects) or −60 mmHg was reached. (1) The linear relationships between DAP and burst strength and between DAP and total MSNA were shifted progressively upward as LBNP increased until the level at which syncope occurred. The relationship between DAP and burst incidence, however, gradually shifted upward from control only to LBNP =−30 mmHg; there was no further upward shift at higher LBNPs. (2) Although the slope of the relationship between DAP and burst strength and between DAP and total MSNA remained constant at all LBNPs tested, except at the level where syncope occurred, the slope of the relationship between DAP and burst incidence was reduced at LBNPs of −40 mmHg and higher ( versus control). (3) In syncopal subjects, the slopes of the relationships between DAP and burst incidence, burst strength, and total MSNA were all substantially reduced during the 1–2 min period prior to the onset of syncope. Taken together, these results suggest baroreflex control over MSNA is progressively modulated as orthostatic stress increases, so that its sensitivity is substantially reduced during the period immediately preceding the severe hypotension associated with orthostatic syncope.  相似文献   
28.
We evaluated the effects of rowing on the morphology and function of the leg extensor muscle in old people. The area and the power of the leg extensor muscle were measured in 15 oarsmen – age [mean (SD)] 65 (3) years; height 171 (4) cm, body mass 68 (6) kg – and in 15 sedentary men – age 66 (4) years, height 170 (4) cm, body mass 67 (7) kg – who were matched on the basis of their body size. The leg extensor muscle area of the oarsmen was larger than that of the sedentary men [77.8 (5.4) vs 68.4 (5.1) cm2, P<0.05]. Also the bilateral leg extension power of the oarsmen was larger than that of the sedentary men [1,624 (217) vs 1,296 (232) W, P<0.05]. Thus, the leg extension power per the leg extensor muscle area was not significantly different between two groups [20.9 (2.0) vs 19.9 (2.1) W·cm–2) and leg extension power was correlated to the leg extensor muscle area (59–89 cm2, r=0.74, P<0.001). Also the 2,000-m rowing ergometer time of the oarsmen [495 (14) s; range 479–520 s] was related to leg extensor muscle area (68–89 cm2, r=0.63, P<0.01). The results suggest that rowing prevents age-related muscle wasting and weakness. Electronic Publication  相似文献   
29.
Natural tooth loss represents a major medical issue within the elderly population, since it impairs masticatory function critical for oral intake of essential nutrition. Contribution of genetic factors has been implicated in the determination of natural tooth loss; degree of reduction in number of natural teeth remaining intact (NTI) varies among individuals; thus, heterogeneity in NTI might reflect genetic variation within the population. One candidate gene, the matrix Gla protein gene (MGP), has been implicated in the pathogenesis of bone loss through a repression of bone/tooth formation. We have investigated a possible association between the CA repeat polymorphism at the human MGP gene locus and the NTI in 458 elderly Japanese women. In 916 chromosomes tested, ten alleles of the polymorphic nucleotide repeat were observed (designated A1–A10), among which five alleles were regarded as major alleles to be tested for the association. Twenty-seven women who possessed an A6 allele (164 bp) had significantly higher NTI than the remaining participants (n=431), who did not carry an allele of that size (mean: 10.0 teeth vs 5.6 teeth; P=0.007, Mann-Whitney test). An eight-year longitudinal follow-up study of NTI suggested that the genetic variations at the MGP locus did not affect the rate of tooth loss in the elderly period. These results suggest that genetic variation at the MGP gene locus is associated with some determinants for tooth loss in elderly women.  相似文献   
30.
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