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   8023篇
  免费   642篇
  国内免费   34篇
耳鼻咽喉   27篇
儿科学   182篇
妇产科学   194篇
基础医学   1051篇
口腔科学   309篇
临床医学   746篇
内科学   1285篇
皮肤病学   139篇
神经病学   856篇
特种医学   312篇
外科学   1066篇
综合类   195篇
一般理论   8篇
预防医学   796篇
眼科学   62篇
药学   578篇
  1篇
中国医学   3篇
肿瘤学   889篇
  2022年   50篇
  2021年   92篇
  2020年   59篇
  2019年   113篇
  2018年   119篇
  2017年   108篇
  2016年   126篇
  2015年   121篇
  2014年   196篇
  2013年   260篇
  2012年   395篇
  2011年   409篇
  2010年   230篇
  2009年   198篇
  2008年   389篇
  2007年   362篇
  2006年   360篇
  2005年   344篇
  2004年   383篇
  2003年   325篇
  2002年   298篇
  2001年   264篇
  2000年   277篇
  1999年   251篇
  1998年   100篇
  1997年   88篇
  1996年   84篇
  1995年   90篇
  1994年   93篇
  1993年   68篇
  1992年   223篇
  1991年   189篇
  1990年   159篇
  1989年   150篇
  1988年   132篇
  1987年   156篇
  1986年   141篇
  1985年   133篇
  1984年   81篇
  1983年   90篇
  1982年   51篇
  1981年   57篇
  1979年   71篇
  1978年   70篇
  1976年   50篇
  1974年   64篇
  1973年   51篇
  1972年   56篇
  1971年   59篇
  1970年   47篇
排序方式: 共有8699条查询结果,搜索用时 15 毫秒
11.
Exposure of ZR-75-1 human breast cancer cells for 48 h to human recombinant interferon alpha (IFN alpha) resulted in increased expression of oestrogen receptors as measured in a whole cell binding assay. This effect was inversely proportional to dose being significant following treatment with 10-100 IU IFN ml-1 and was only observed at a low initial cell plating density. The extent of the increase in oestrogen receptor levels ranged from 1.2- to 7.2-fold following treatment with 10 IU IFN ml-1. No increase in progesterone receptor expression was observed under the same experimental conditions. Concentrations of IFN which increased oestrogen receptor levels had no effect on cell proliferation. IFN (500 IU ml-1) inhibited cell proliferation and the combination of this treatment with tamoxifen (2 microM) had a greater anti-proliferative effect than either drug alone although there was no evidence of synergism. However, a 5-day pretreatment of cells with IFN (10 IU ml-1) markedly sensitised them to the growth-inhibiting effect of a subsequent 6-day exposure to tamoxifen.  相似文献   
12.
This case study highlights the important contribution of nursing in obtaining an accurate health history. The case discussed herein initially appeared to be neurogenic diabetes insipidus (DI) secondary to a traumatic brain injury. The nursing staff, by reviewing the patient's health history with his family, discovered a history of polydipsia and long-standing lithium use. Lithium is implicated in drug-induced nephrogenic DI, and because the patient had not received lithium since being admitted to the hospital, his treatment changed to focus on nephrogenic DI. By combining information from the patient history, the physical examination, and radiologic and laboratory studies, the critical care team demonstrated that the patient had been self-treating his lithium-induced nephrogenic DI and developed neurogenic DI secondary to brain trauma. Thus successful treatment required that nephrogenic and neurogenic DI be treated concomitantly.  相似文献   
13.
It is estimated that 5% to 10% of pancreatic cancer cases are attributable to hereditary factors. We believe that the number of cases that are genetic in etiology are even greater, however, based not on a classic autosomal dominant pattern of inheritance but rather when one takes into account low-penetrant inherited susceptibility factors. There is also a growing recognition that the development of pancreatic cancer in pancreatic cancer-prone families is dependent not only on genetic variables but on nongenetic factors. The aim of this article is to review the challenges in identifying pancreatic cancer-prone families and how environmental factors interact with genetic factors in these families.  相似文献   
14.
Glucose is provided to cells by a family of glucose transport facilitators known as GLUTs. These transporters are expressed in a tissue specific manner and are overexpressed in many primary tumors of these tissues. Regulation of glucose transport facilitator expression has been demonstrated in endometrial tissue and endometrial adenocarcinoma. The following experiments were conducted to quantify and localize the expression of GLUT1 and GLUT8 in benign endometrium and compare this expression to endometrial cancer. Endometrial tissue samples were obtained from random hysterectomy specimens of patients with benign indications for surgery and endometrial cancer. Immunoblot and immunolocatization studies were performed using GLUT1 and GLUT8 specific antisera. Endometrial samples from 65 women who had undergone hysterectomy were examined (n=38 benign, n=27 malignant). A 44 and a 35.4 kDa immunoreacive species was demonstrated in endometrium and endometrial cancer for GLUT1 and GLUT8, respectively. Upregulation of GLUT1 expression was demonstrated with increasing grade of tumors (P<0.002). GLUT8 expression was increased in all tumor subtypes compared to atrophic endometrium (P<0.001). Apical localization by GLUT1 and GLUT8 was demonstrated in endometrial glands. GLUT1 and GLUT8 demonstrated diffuse intracellular localization in the cancer subtypes. GLUT1 and GLUT8 are expressed in both human endometrium and endometrial cancer. There appears to be a step-wise progression in GLUT1 and GLUT8 expression as tumor histopathology worsens. GLUT1 and GLUT8 may be important markers in tumor differentiation, as well as providing energy to rapidly dividing tumor cells.  相似文献   
15.
16.
Objective: Mental nerve block is frequently used to aid repair of facial lacerations; both percutaneous and intraoral approaches to blocking this nerve are used, but have never been compared. The authors compared the two techniques for pain of administration and effectiveness of anesthesia. Methods: A prospective, randomized, single-blind, crossover study was conducted using ten healthy volunteers aged 22 to 33 years. Patients having prior experience with mental nerve blocks, lidocaine allergy, active oral/facial infection, or previous facial fractures were excluded. Bilateral mental nerve blocks were done using intraoral technique on one side and percutaneous technique on the other. Both techniques were used by the same investigator and were carried out with 27-gauge needles and 2.5 mL of 2% buffered lidocaine at room temperature injected over 20 seconds. The oral mucosa was topically anesthetized with viscous lidocaine for 1 minute prior to intraoral injection. The orders of the blocks and sides of the face anesthetized were randomized. Subjective and objective pain (visual-analog scale), efficacy (anesthesia of lower lip), time to onset, and duration of anesthesia were evaluated. Results: The intraoral technique was subjectively less painful than the percutaneous approach in nine of ten subjects (p = 0.02). Scores on the visual-analog pain scale were significantly lower for the intraoral technique (p = 0.03). Intraoral injection produced lower-lip anesthesia in 10/10 subjects versus 7/10 for percutaneous (p = 0.25). Times to onset (approximately 1–2 minutes) and durations of anesthesia (approximately one hour) were similar for the two techniques. Conclusion: The intraoral approach to the mental nerve block with adjunctive topical anesthesia was subjectively and objectively less painful than the percutaneous approach without adjunctive anesthesia. While the intraoral approach had a greater efficacy of lower-lip anesthesia and a longer duration of action, these differences were not statistically significant.  相似文献   
17.
Time-dependent changes in mesolimbic dopamine (DA) function are believed to play a role in behavioral sensitization and drug craving experienced during withdrawal from chronic cocaine administration. The present study utilized intravenous (IV) cocaine self-administration coupled with intracranial microdialysis in rats to investigate time dependent changes during withdrawal from chronic cocaine exposure. Following 2 weeks of IV cocaine self-administration, rats were allowed contingent access to cocaine at 1 and 7 days of withdrawal while extracellular levels of DA were measured from the ventral striatum. A second group of animals received yoked, noncontingent cocaine for 2 weeks and were then administered noncontingent cocaine on days 1 and 7 of withdrawal. In addition, a third group of animals received 2 weeks of yoked saline followed by noncontingent cocaine 1 day after withdrawal. There were no significant differences between groups for the overall cocaine dosage or temporal pattern of infusions on days 1 and 7 of withdrawal. Basal extracellular DA concentrations did not differ between any treatment groups at either withdrawal time. Extracellular DA levels were increased throughout the session on both days; however, the increases at day 7 were significantly less than day 1 for both contingent and noncontingent conditions. DA overflow on day 1 did not differ between animals receiving chronic yoked cocaine or saline. These results suggest that tolerance-like attenuation to the DA-elevating effects of cocaine is not apparent early in withdrawal, but does develop by later time points. DA release in the ventral striatum may not be directly related to cocaine self-administration following withdrawal, since DA levels were attenuated after 7 days of withdrawal while responding for cocaine was unaltered.  相似文献   
18.
19.
Thrombosis of the inferior vena cava by seminoma   总被引:1,自引:0,他引:1  
We report a case of metastatic seminoma that caused thrombosis and obstruction of the inferior vena cava. The pathogenesis of this rare clinical entity is discussed. The diagnostic studies for detection of vena caval thrombosis and clinical management strategies are reviewed.  相似文献   
20.
This prospective study compared 30 patients randomly assigned to either a home exercise program or supervised outpatient physical therapy following arthroscopic partial medial meniscectomy. Their knee functions were assessed at 2, 4, and 8 weeks postoperatively using isokinetic analysis and subjective questionnaires. At each evaluation, the home exercise group performed as well or better than the supervised physical therapy group. There were no statistically significant differences between the two groups. At 4 weeks postoperation, the mean percent deficit in torque (strength) between the affected and unaffected limbs was 22.1% in the supervised rehabilitation group and 22.0% in the home exercise. The percent deficit in terms of endurance was 7.7% in the supervised group and 3.6% in the home group. Similar results were noted with regard to the patients' subjective evaluations of their knee function and ability to resume work and recreational activities. We conclude that a well-planned, unsupervised home exercise knee rehabilitation program can produce equally good postoperative recovery as compared to a supervised outpatient physical therapy regimen in properly selected patients following arthroscopic partial meniscectomy of the knee.  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