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   24027篇
  免费   1942篇
  国内免费   164篇
耳鼻咽喉   364篇
儿科学   698篇
妇产科学   363篇
基础医学   3073篇
口腔科学   323篇
临床医学   2099篇
内科学   5443篇
皮肤病学   646篇
神经病学   2041篇
特种医学   862篇
外科学   3358篇
综合类   425篇
一般理论   26篇
预防医学   2297篇
眼科学   480篇
药学   1570篇
中国医学   64篇
肿瘤学   2001篇
  2023年   123篇
  2022年   255篇
  2021年   440篇
  2020年   302篇
  2019年   439篇
  2018年   501篇
  2017年   475篇
  2016年   486篇
  2015年   548篇
  2014年   735篇
  2013年   966篇
  2012年   1438篇
  2011年   1429篇
  2010年   869篇
  2009年   718篇
  2008年   1384篇
  2007年   1577篇
  2006年   1382篇
  2005年   1392篇
  2004年   1249篇
  2003年   1310篇
  2002年   1240篇
  2001年   471篇
  2000年   514篇
  1999年   449篇
  1998年   314篇
  1997年   268篇
  1996年   242篇
  1995年   233篇
  1994年   184篇
  1993年   167篇
  1992年   332篇
  1991年   268篇
  1990年   299篇
  1989年   243篇
  1988年   240篇
  1987年   217篇
  1986年   196篇
  1985年   225篇
  1984年   155篇
  1983年   120篇
  1982年   126篇
  1981年   93篇
  1980年   99篇
  1979年   128篇
  1978年   123篇
  1977年   105篇
  1976年   106篇
  1974年   106篇
  1973年   108篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
Our previous study demonstrated that pro-gastrin-releasing peptide(31–98), or ProGRP, is a specific tumor marker in patients with small cell lung carcinoma (SCLC). Using a newly developed, highly sensitive enzyme-linked immunosorbent assay (ELISA) for ProGRP, we analyzed 1,446 samples including those obtained from 478 lung cancer patients to evaluate the clinical usefulness of this ELISA. Several properties indicated that ProGRP is a useful tumor marker for SCLC. First, ProGRP was specifically elevated in SCLC patients. In non-SCLC patients and patients with non-tumorous lung diseases, its serum level was very rarely elevated. Secondly, ProGRP was a reliable marker, in terms of the marked elevation of serum ProGRP levels in SCLC patients. Thirdly, serum ProGRP levels were elevated in SCLC patients even at a relatively early stage of this disease. Fourthly, changes in the serum ProGRP level showed an excellent correlation with the therapeutic responses in SCLC patients. Neuron-specific enolase (NSE) is accepted as a tumor marker of SCLC patients. With the aim of comparing ProGRP and NSE as tumor markers for SCLC patients, we measured serum NSE levels in all samples collected in the present study. We found that ProGRP was superior to NSE in terms of sensitivity, specificity and reliability. Therefore, we consider that ProGRP can play a major role as a clinical tumor marker for SCLC patients.  相似文献   
102.
Because of concern about psoralen-induced phototoxicity and photocarcinogenesis, we investigated the effects of dietary lipids in a mouse model in which 8-methoxypsoralen (8-MOP) and UVA (PUVA) therapy has been shown to be carcinogenic. SKH-Hr-1 hairless albino mice were fed diets containing either omega-3 or omega-6 fatty-acid sources (menhaden oil and corn oil, respectively). After 2 weeks on the diets, the mice were treated topically with 8-MOP and then exposed to UVA (5 J/cm2). Mice receiving the omega-3 fatty-acid source exhibited a marked decrease in inflammatory response and a more rapid repair, as expressed both grossly and microscopically. In support of the latter response, i.e. repair, ornithine decarboxylase activity was about 20% greater in animals receiving the omega-3 fatty-acid source. The effects of the dietary fatty acid sources on PUVA tumorigenesis were examined in long-term studies in which animals were treated topically with 0.01% 8-MOP thrice weekly after which they were exposed to UVA (1 J/cm2). These studies indicated that a dietary lipid rich in omega-3 fatty acid and known to exhibit anti-inflammatory properties can markedly ameliorate the course of PUVA toxicity but does not impede the course of PUVA tumorigenesis  相似文献   
103.
Autoimmune progesterone dermatitis is a rare condition, characterized by recurrent premenstrual exacerbations of a dermatosis, in which sensitivity to progesterone can be demonstrated. The sensitizing mechanism is unknown. The aim of this study was to test the hypothesis that cross-sensitivity between steroid groups could induce allergy to endogenous progesterone in these patients. 5 patients with autoimmune progesterone dermatitis and 1 with oestrogen-sensitive dermatitis have been patch tested with a corticosteroid series, conjugated oestrogen 1% in petrolatum (pet.), and 17-α-OH-progesterone 2% pet. There were no immediate or delayed reactions at 2 and 4 days to any steroid group. We have therefore been unable to demonstrate steroid cross-sensitivity, or a use for 17-α-OH-progesterone in the investigation of oestrogen - and progesterone-sensitive dermatoses.  相似文献   
104.
To evaluate the clinical usefulness of gallium 67 imaging in the detection of gastrointestinal (GI) non-Hodgkin's lymphoma (NHL) and in the assessment of the therapeutic effects, images were reviewed in 24 cases (25 lesions: stomach, 20; ileum, 2; and terminal ileum and/or cecum, 3) and were compared using barium studies and, in 16 cases, computerized tomography (CT). In all, 23 (92.0%) of the 25 lesions were detected by67Ga citrate imaging, the barium studies detected all 25, and CT detected 15 of 16 lesions (93.8%). The two lesions not identified by imaging and the one not found by CT were the smallest of all. In 2 (8.7%) of the 23 lesions positively identified by67Ga-citrate imaging, both CT and imaging revealed the extent of the tumor more accurately than did the barium studies. In all but one of the patients, a close correlation existed between the imaging results and the therapeutic effects. These data suggest that67Ga imaging is useful in conjunction with CT and barium studies for the detection of GI NHL and for the assessment of both the spatial extent of disease and the therapeutic effects, although a lack of67Ga uptake after therapy does not always indicate a good therapeutic effect.  相似文献   
105.
106.
We report the imaging findings of an abdominal aggressive angiomyxoma, which communicated with the gastrointestinal tract. The literature on this rare tumor is reviewed.  相似文献   
107.
Cardiac ultrasound and upper gastrointestinal endoscopy are relatively old technologies. With the introduction of new ultrasound probes and by incorporating ultrasound technology into conventional endoscopes, ‘new tricks’ in cardiac imaging were discovered. Posterior structures of the heart are now able to be imaged clearly by the ultrasound probe from the oesophagus. Consequently, better resolution of cardiac anatomy allows more accurate diagnosis of cardiac pathologies which is not possible using conventional transthoracic (TT) approach. Over a period of two years, 1200 cases of transoesophageal echocardiography (TOE) were undertaken in our institution. The major indications were diseases of the aorta (10%), source of cardioembolism (28%), assessment of native and prosthetic valve function (20%), suspected endocarditis and its complication (17%), pre and post percutaneous transluminal mitral valvotomy (PTMV [13%], congenital heart disease (2%) and others (10%). The greatest impact with TOE is in the diagnosis of aortic dissection and transection, TOE is superior to conventional TT approach in detecting potential source of embolism, valvular vegetations and its complication, native and prosthetic valve dysfunction and LA thrombus prior to PTMV. Observations by TOE such as spontaneous echo contrast (SEC) in the left atrium open new challenges for further research in its role in the pathogenesis of LA thrombus and its association with cardioembolic event. Other areas of interest include; reclassification of distal aortic dissection and the use of TOE in intra-operative work.  相似文献   
108.
109.
110.
Spinal cords of myelin-deficient and normal age-matched (control) rats were removed and their conduction and pharmacological properties studied in an in vitro brain slice chamber. The conduction velocity of the myelin-deficient dorsal column axons was reduced to about 25% of control axons; however, the amyelinated myelin-deficient axons displayed refractory periods and the ability to sustain high-frequency action potential discharge similar to that of dorsal column axons in control rats. Pharmacological results suggest that the myelin-deficient dorsal column axons qualitatively express a normal complement of ion channels and receptors. The demonstration of a normal representation of channels and receptors on these axons supports the proposal that the oligodendrocyte, and not the axon, is the site of the primary defect in the myelin-deficient rat mutant. It is concluded that, unlike acutely demyelinated axons which display marked frequency-dependent conduction block, amyelinated axons of the myelin-deficient rat spinal cord develop compensatory mechanisms to stabilize action potential conduction.  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