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   12516篇
  免费   952篇
  国内免费   65篇
耳鼻咽喉   219篇
儿科学   403篇
妇产科学   363篇
基础医学   1447篇
口腔科学   233篇
临床医学   1541篇
内科学   2250篇
皮肤病学   214篇
神经病学   1249篇
特种医学   498篇
外科学   1556篇
综合类   216篇
一般理论   13篇
预防医学   1465篇
眼科学   487篇
药学   696篇
中国医学   6篇
肿瘤学   677篇
  2022年   84篇
  2021年   226篇
  2020年   101篇
  2019年   166篇
  2018年   198篇
  2017年   156篇
  2016年   188篇
  2015年   208篇
  2014年   301篇
  2013年   449篇
  2012年   642篇
  2011年   683篇
  2010年   396篇
  2009年   377篇
  2008年   627篇
  2007年   699篇
  2006年   695篇
  2005年   661篇
  2004年   638篇
  2003年   557篇
  2002年   524篇
  2001年   343篇
  2000年   315篇
  1999年   330篇
  1998年   105篇
  1997年   110篇
  1996年   92篇
  1995年   104篇
  1994年   92篇
  1993年   87篇
  1992年   194篇
  1991年   203篇
  1990年   208篇
  1989年   168篇
  1988年   167篇
  1987年   190篇
  1986年   169篇
  1985年   200篇
  1984年   120篇
  1983年   101篇
  1982年   83篇
  1981年   82篇
  1979年   113篇
  1978年   111篇
  1977年   82篇
  1976年   84篇
  1974年   99篇
  1973年   96篇
  1972年   83篇
  1970年   86篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
51.
A controlled randomized clinical trial was undertaken to assess the ability of combined non-specific and specific immunotherapy to alter the disease-free interval and overall survival of patients with Stage B or C large bowel cancer. The immunotherapy consisted of a 2 year programme of vaccinations with BCG and neuraminidase-treated autologous tumour cells. Three hundred and one patients entered the trial. At 5 years of follow-up there is no evidence that this form of immunotherapy can alter either the disease-free interval or survival in this group of patients.  相似文献   
52.
53.
When glaucoma medication fails to adequately control intraocular pressure (IOP), a second medication is frequently added. Before adding a second drug to patients whose IOP was no longer controlled by 0.5% timolol, we tested the effect of switching to another beta blocker, levobunolol (0.5 or 1%). We also evaluated the effect of study participation on compliance in the control group continuing to receive 0.5% timolol. In each treatment group, the IOP of approximately 30-40% of the patients was successfully controlled for the 3-month study period. The remaining patients did not exhibit significant pressure reductions and were dropped from the study within 2 weeks. We concluded that (1) the results of 'switch' studies without a control group must be interpreted carefully, and (2) the initiation of a 'new regimen' with an equieffective beta blocker may be sufficient to increase compliance and thereby control IOP.  相似文献   
54.
We report an analysis of the qualitative phase of a study of patients' and carers' views of primary care services, focusing on their experiences of access to face-to-face general practitioner (GP) consultations during the period when new access policies were being implemented. Practices interpreted the new policy in various ways; restricted interpretations, including restriction of access to telephone booking, could cause distress to patients. Patients and carers welcomed flexible interpretations of the policy that offered choice, such as a choice of GP, or of booking in advance.  相似文献   
55.
56.
Assessment of cardiovascular autonomic function.   总被引:5,自引:0,他引:5  
Autonomic assessment has played an important role in elucidating the role of the autonomic nervous system in diverse clinical and research settings. The techniques most widely used in the clinical setting entail the measurement of an end-organ response to a physiological provocation. The non-invasive measures of cardiovascular parasympathetic function involve the analysis of heart rate variability while the measures of cardiovascular sympathetic function assess the blood pressure response to physiological stimuli. Prolonged tilt-table testing, with or without pharmacological provocation, has become an important tool in the investigation of a predisposition to neurally mediated (vasovagal) syncope. Frequency domain analyses of heart rate and blood pressure variability, microneurography, occlusion plethysmography, laser Doppler imaging and flowmetry, and cardiac sympathetic imaging are currently research tools but may find a place in the clinical assessment of autonomic function in the future.  相似文献   
57.
In part I of this review the principles governing the uses of analgesics and sedatives in the ITU were considered. In part II we shall review the drugs available considering first, symptomatic therapy and secondly, regional analgesia.  相似文献   
58.
59.
Seventy-three patients with small (less than 6 cm in diameter) abdominal aortic aneurysms (AAAs) were selected for nonoperative management and followed up with sequential ultrasound size measurements. Fifty-four men and 19 women, 51 to 89 years of age (mean 70 years), had an initial mean AAA size of 4.1 cm (anteroposterior) x 4.3 cm (lateral) diameter, with a calculated elliptic cross-sectional area of 14.3 cm2. After a mean of 37 months of follow-up, AAA area increased at a mean rate of 20% per year (3 cm2 yr; 0.4 to 0.5 cm/yr diameter). Expansion rate was not affected by initial aneurysm size. During follow-up, only 3 patients (4%) required urgent operation (1 died), 26 patients (36%) died of non-AAA causes, and 26 patients (36%) underwent elective AAA repair because of progressive size increase (1 died). Elective operations were performed at the rate of 10% per year, when mean AAA size had increased to 22 cm2 (5.1 cm in diameter). Multiple regression analysis of clinical parameters available at presentation indicated that subsequent elective AAA repair was predicted by younger age at diagnosis and larger initial aneurysm size. As anticipated, patients who underwent surgery had more rapid aneurysm expansion (5.3 cm2/yr) compared with patients who did not undergo surgery (1.6 cm2/yr; p less than 0.05). This difference was caused by more rapid expansion during later follow-up intervals among patients selected for operation and was not predicted by the change in aneurysm size observed during initial ultrasonographic follow-up. Final aneurysm size was predicted by initial size, duration of follow-up, and both systolic and diastolic pressure.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   
60.
BACKGROUND. The noninvasive prediction of pulmonary-capillary wedge pressure (PCWP) is important for the recognition and treatment of a variety of cardiovascular disorders. The response of the arterial pressure to the Valsalva maneuver has been shown to correlate with the PCWP. We therefore devised a noninvasive method to measure this pressure response at the bedside and correlated these measurements with the PCWP measured directly with a pulmonary-artery catheter. METHODS. Simultaneous, blinded, noninvasive measurements of the ratio of the final amplitude to the initial amplitude of the pulse wave form during the stress phase of the Valsalva maneuver (pulse-amplitude ratio) and direct measurements of the PCWP were obtained in 20 clinically stable patients and in 14 clinically unstable patients who were receiving vasoactive agents, 12 of whom also had endotracheal tubes in place. RESULTS. Using linear regression analysis, we found that the pulse-amplitude ratio strongly correlated with the measured PCWP over a range of base-line values from 4 to 32 mm Hg for the 20 clinically stable patients (R2 = 0.80) and the 14 clinically unstable patients (R2 = 0.85). The method also correctly predicted changes in the PCWP after the administration of nitroglycerin or furosemide and after expansion of the intravascular volume (R2 = 0.79). CONCLUSIONS. These preliminary data indicate that a simple noninvasive method can accurately predict the PCWP and changes in the PCWP in response to medical therapy.  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