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   18194篇
  免费   1654篇
  国内免费   74篇
耳鼻咽喉   153篇
儿科学   698篇
妇产科学   586篇
基础医学   2440篇
口腔科学   384篇
临床医学   1968篇
内科学   3187篇
皮肤病学   269篇
神经病学   1829篇
特种医学   1174篇
外科学   2157篇
综合类   357篇
一般理论   21篇
预防医学   1929篇
眼科学   338篇
药学   1424篇
中国医学   21篇
肿瘤学   987篇
  2021年   243篇
  2020年   196篇
  2019年   227篇
  2018年   296篇
  2017年   241篇
  2016年   241篇
  2015年   293篇
  2014年   388篇
  2013年   571篇
  2012年   787篇
  2011年   799篇
  2010年   511篇
  2009年   439篇
  2008年   733篇
  2007年   780篇
  2006年   714篇
  2005年   680篇
  2004年   604篇
  2003年   639篇
  2002年   580篇
  2001年   559篇
  2000年   560篇
  1999年   514篇
  1998年   278篇
  1997年   260篇
  1996年   258篇
  1995年   212篇
  1994年   192篇
  1993年   181篇
  1992年   406篇
  1991年   426篇
  1990年   429篇
  1989年   400篇
  1988年   424篇
  1987年   430篇
  1986年   365篇
  1985年   386篇
  1984年   272篇
  1983年   237篇
  1982年   155篇
  1979年   260篇
  1978年   205篇
  1977年   151篇
  1976年   180篇
  1975年   142篇
  1974年   180篇
  1973年   172篇
  1972年   151篇
  1969年   169篇
  1968年   146篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
11.
This article considers the unique challenges and opportunities that health care providers (HCPs) face when they address the sexual and reproductive health and rights of young women accessing services. Some of the difficulties that HCPs encounter in their work are highlighted, including poor remuneration, the impact of their personal biases and the effect of an under-equipped working environment. The financial, logistical and emotional challenges young people face in accessing services are also described, as well as some small changes that could promote fruitful partnerships between HCPs and their young clientele. Also considered is how international documents concerning reproductive health can be utilized as advocacy tools to ensure that, when governments speak of making young people's needs a priority, resources are also made a priority-so that reproductive health can become a reality for all young people.  相似文献   
12.
Abstract: Background : Women are increasingly being asked to consider participating in medical research. We sought to investigate views of women who participated in and declined to participate in a study that was part of a program of maternity care research. Methods : An exploratory study using focus group interviews and semistructured interviews was conducted. A purposive sample of 17 postnatal women who had participated in research, from a hospital in the North West of England, were interviewed. An open coding mechanism to identify emergent themes was used for the analysis of data. Results : Of women who had not declined to participate in any research, the following themes were identified: altruism versus self‐protection, enhanced versus inferior care, professional guidance versus self‐direction, and welcome versus unacceptable methodology. Of women who had participated in some research but declined to participate in other research, the following themes were identified: feeling disempowered by the process, inability to believe equipoise existed, and practical inconvenience. Conclusions : These findings suggest that although health care researchers adopt an individualistic approach to care, they may fail to adopt a similar approach within research. What is important and acceptable to women needs to be ascertained to develop appropriate research strategies. This plan will ensure that research is carried out to the highest ethical standard, which may increase recruitment rates.  相似文献   
13.
14.
15.
16.
Idiopathic retroperitoneal fibrosis. A retrospective analysis of 60 cases   总被引:5,自引:0,他引:5  
Sixty patients with idiopathic retroperitoneal fibrosis presenting between 1965 and 1984 are reviewed. Their mean age at presentation was 56 years and the male:female ratio was 3:1. The commonest presenting symptoms were flank and abdominal pain, weight loss, nausea and polyuria. Physical examination was usually normal, expect for the presence of hypertension. Anaemia and elevation of erythrocyte sedimentation rate were usually present. Proteinuria was found in less than a third of patients at presentation and significant bacteriuria was uncommon. The correct diagnosis was made or suspected in very few patients before referral. The cumulative actuarial survival rate was 86% at 1 year and 78% at 2 years. Seventeen patients died; they were significantly older and more uraemic at the time of referral than those who survived. A few patients did well with either corticosteroid therapy or ureterolysis alone. In the majority, both operation and steroid treatment were necessary. In bilateral obstruction with residual function in both kidneys, bilateral ureterolysis proved superior to unilateral operation (each followed by steroid therapy) in conserving renal function. Operation alone or steroid therapy alone should be considered in cases where steroids or surgery respectively present particular hazards. The less traumatic unilateral operation should be considered in poor risk patients and in those whose renal function is absent on one side. In many survivors, disease activity has persisted for many years. Life-long follow-up is recommended.  相似文献   
17.
The purpose of this study was to determine if changes in hindlimb motoneuron membrane electrical properties occur 4–6 months after spinal transection in the adult animal. Eight acute and nine chronic animals were spinalized at T12. Intracellular recordings from motoneurons innervating the triceps surae were performed. Membrane electrical properties, including resting potential, action potential peak amplitude, afterhyperpolarization duration, rheobasic current, input resistance and axonal conduction velocity were measured. There were no statistical differences found between group means or frequency distributions in the membrane properties of motoneurons assessed from acute and chronic spinal animals. Thus, alteration of motoneuron membrane properties does not appear to be a major contributing factor to the hyperexcitable hindlimb reflex activity demonstrated by chronic spinal animals.  相似文献   
18.
BACKGROUND: There is no consensus regarding the optimal rate of follow-up in the post-bariatric surgery patient population. METHODS: The records of all patients who underwent laparoscopic Roux-en-Y gastric bypass from 2001 to 2003 were reviewed. Using patient zip codes, travel distances were calculated between the patients' places of residence and our clinic. Patients were then assigned to 1 of 3 cohorts according to the following distances: (1) < 50 miles, (2) 50 to 100 miles, and (3) > 100 miles. Patient compliance with follow-up appointments at 3 weeks, 3 months, 6 months, 9 months, and 12 months was analyzed. Linear trends were identified using the Mantel-Haenszel test. Age and sex were analyzed as possible predictors of compliance using the chi(2) test. P values < .05 were considered statistically significant. RESULTS: The study group comprised 150 patients (127 females and 23 males). The 3 cohorts contained 115, 21, and 14 patients, respectively. All patients in each cohort were compliant with the 3-week follow-up appointment. Although there were differences in compliance between cohorts at each of the remaining appointments, only the 9-month (70.3% vs 61.9% vs 35.7%) visit showed statistical significance (P = .035). The 6-month visit trended toward significance (85.2% vs 76.2% vs 64.3%; P = .088). Males were more likely to be compliant with the 12-month follow-up (P = .040). When controlling for sex, travel distance was also a predictor of compliance at this follow-up visit (P = .024). Age was not predictive of compliance (P = .827). CONCLUSION: Based on our findings, we conclude that travel distance from the clinic does not significantly affect compliance at the initial follow-up, 3-month, and 12-month appointments. However, distance does tend to affect compliance at the 6-month appointment and significantly affects compliance at the 9-month appointment. Males are more likely to be compliant at the 12 month follow-up visit. We must continue to strive for 100% follow-up in our post-bariatric surgery patients.  相似文献   
19.
Experience with intraaortic balloon counterpulsation   总被引:6,自引:0,他引:6  
An eleven-year experience with intraaortic balloon pumping (IABP) or counterpulsation in 637 patients was analyzed with respect to early and late results. Intraaortic balloon pumping was employed for left ventricular pump failure, for coronary insufficiency, and in association with cardiac operations. Late results were analyzed by follow-up of 283 (93%) of the 304 patients leaving the hospital, and were studied with respect to duration of survival, activity status, occupational status, presence of cardiac symptoms, use of cardiac medications, and presence of lower extremity claudication. Early results were analyzed for hospital survival (304/637 [48%]). Patient complications of IABP included wound infection (1/637 or 0.2%), vascular complications (66/637 or 10.4%), and balloon failure (8/637 or 1.3%). No deaths were attributable to complications of IABP. Survival did not correlate with the duration of IABP. Survival was improved in patients who had revascularization in association with IABP.  相似文献   
20.
The relative importance of different proteinases, and their inhibition, in the breakdown of human endothelial basement membrane (BM) by MDA-MB-231 and MCF7ADR human breast cancer cell lines has been studied using 35S-labelled BM-coated 96-well culture plates. Basement membrane degradation (BMD) was independent of cell proliferation above the seeding density. Inhibitors of aspartic (pepstatin and PD 134678-0073) and cysteine proteinases (E64) had little effect on BMD under normal culture conditions, suggesting that cathepsins D, B and L have only a minor role. In contrast, inhibitors of urokinase-type plasminogen activator (uPA) and/or plasminogen activation to plasmin (aprotinin, amiloride, EACA, tranexamic acid, anti-uPA antibody) all reduced BMD by MDA-MB-231 cells by approximately 30-40%, but only in the presence of serum or plasminogen. BB94, an inhibitor of matrix metalloproteinases (MMPs), also reduced BMD by about 30% under these conditions but was similarly effective in serum-free medium. Combinations of BB94 with any of the uPA/plasminogen activation inhibitors in serum-containing medium had additive effects, while BB94 with pepstatin and E64 under serum-free conditions reduced BMD to 16% of control. Serum-containing conditioned medium exhibited appreciable BMD, largely due to aprotinin-inhibitable activity. Although small reductions in cell proliferation were seen with some inhibitors, the combination of BB94 with E64 or E64d reduced the cell population by about 60% under serum-containing conditions. These in vitro observations suggest that combinations of proteinase inhibitors, particularly of uPA/plasminogen activation and MMPs, may merit clinical evaluation as potential antimetastatic therapy for breast cancer.  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