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   37570篇
  免费   2091篇
  国内免费   188篇
耳鼻咽喉   341篇
儿科学   555篇
妇产科学   391篇
基础医学   4988篇
口腔科学   1139篇
临床医学   2393篇
内科学   9009篇
皮肤病学   994篇
神经病学   2688篇
特种医学   1451篇
外科学   6667篇
综合类   194篇
一般理论   1篇
预防医学   1058篇
眼科学   835篇
药学   2847篇
中国医学   71篇
肿瘤学   4227篇
  2023年   157篇
  2021年   668篇
  2020年   379篇
  2019年   473篇
  2018年   642篇
  2017年   574篇
  2016年   644篇
  2015年   714篇
  2014年   889篇
  2013年   1136篇
  2012年   1728篇
  2011年   1936篇
  2010年   1138篇
  2009年   1004篇
  2008年   1667篇
  2007年   1696篇
  2006年   1731篇
  2005年   1849篇
  2004年   1718篇
  2003年   1731篇
  2002年   1674篇
  2001年   1357篇
  2000年   1383篇
  1999年   1279篇
  1998年   496篇
  1997年   430篇
  1996年   389篇
  1995年   338篇
  1994年   312篇
  1993年   303篇
  1992年   866篇
  1991年   768篇
  1990年   755篇
  1989年   719篇
  1988年   724篇
  1987年   645篇
  1986年   627篇
  1985年   611篇
  1984年   412篇
  1983年   335篇
  1982年   164篇
  1980年   154篇
  1979年   328篇
  1978年   221篇
  1977年   162篇
  1975年   160篇
  1974年   222篇
  1973年   156篇
  1972年   169篇
  1971年   150篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
102.
103.
104.
Intracranial trajectories of sympathetic nerve fibers originating in the superior cervical ganglion (SCG) in the rat were investigated by means of anterograde labeling following the injection of wheat germ agglutinin-horseradish peroxidase conjugate (WGA-HRP) into the unilateral SCG. The trajectory of the sympathetic fiber innervating the pineal gland and its continuing structures was found advancing along the abducent nerve, through the cavernous plexus, then along the trochlear nerve. Labeled sympathetic fibers showed two patterns of distribution in the blood vessels on the basal surface of the brain. The sympathetic fibers originating in the unilateral SCG were intermingled with those fibers from the contralateral SCG in the pineal gland, its continuing structures and the choroid plexus of the third ventricle as well as in the cerebral blood vessels.  相似文献   
105.
106.
107.
Recently, we found CD3-CD4(bright) cells with comparative specificity for normal rat liver. In the current study, we investigated the type and form of both CD3-CD4(bright) cells and CD3-CD4(dull) cells in the rat liver. The surface phenotype of hepatic mononuclear cells in Lewis rats was identified by using monoclonal antibodies including anti-CD4, anti-CD3, and antimacrophage in conjunction with two- or three-color immunofluorescence analysis. CD3-CD4(bright) cells and CD3-CD4(dull) cells were examined morphologically using May-Giemsa staining and scanning electron microscopy. The distribution of CD3-CD4(bright) cells and CD3-CD4(dull) cells 48 hours after intravenous administration of liposome-encapsulated dichloromethylene diphosphate was also investigated. In comparison to CD3-CD4(dull) cells, CD3-CD4(bright) cells were slightly larger macrophages with abundant cytoplasmic granules, being present with comparative specificity for normal rat liver and showing negligible effects by intravenous liposome-encapsulated dichloromethylene diphosphate administration. These data suggest that in normal young rat liver these CD3-CD4(dull) and CD3-CD4(bright) cells may be dendritic cells and Kupffer cells that shift from the liver to the spleen or vice versa. These cells may also be able to locally proliferate in liver or spleen due to changes in the developing liver.  相似文献   
108.
Background: Between September 1992 and September 1996, we performed 88 VATS (video-assisted thoracic surgery) lobectomies and two VATS pneumonectomies. Methods: The indications for surgery were 68 cases of lung cancer, nine cases of bronchiectasis, six cases of tuberculosis, and seven cases of benign lesions. Of the 68 cases of lung cancer, 36 were treated by VATS lobectomy with extended lymph node dissection for clinical stage I lung cancer, making full use of recently developed devices for thoracoscopic surgery, such as roticulating endoscissors, miniretractors, endoclips, and harmonic scalpels. Results: Twenty-four lymph nodes were resected on average (range, 10 to 51) by VATS. This number was comparable to lymph nodes resected in open thoracotomy during the same period. Among the 36 patients who underwent extended lymph node dissection, 20 showed no lymph node metastasis postoperatively (stage I), while 16 had N1 or N2 cancer. All patients with stage I cancer have survived 4 to 36 months (median: 17 months) with no signs of recurrence. Conclusions: This survival of stage I lung cancer after VATS is comparable to that of open thoracotomy. We thus believe that VATS lobectomy with extended lymph node dissection can be an alternative to standard posterolateral thoracotomy for stage I lung cancer. Received: 10 May 1996/Accepted: 19 November 1996  相似文献   
109.
In addition to estrogen widely used all over the world for the prevention of postmenopausal osteoporosis, calcitonin and vitamin D derivatives are commonly employed to treat established osteoporosis at higher age in Japan. In order to critically assess the usefulness of vitamin D derivatives and calcitonin alone or in combination on the advancement of vertebral deformity at higher age, 32 osteoporotic patients with vertebral deformity with the mean age of 79 were randomly divided into 4 groups with indistinguishable age and severity of the vertebral deformity. Group 1 served as the control without specific medications for osteoporosis. Group 2 was treated with 10 units elcatonin (eel calcitonin derivative) injected intramuscularly twice a week. Group 3 was given 0.75 to 1.5μg/day 1α (OH) vitamin D3 orally. Group 4 was given a combination of treatments used in Groups 2 and 3. In the lateral X-ray film of the spine taken prior to the test and every 6 months thereafter, the shape of the vertebral body T8 through L4 was monitored by measuring the anterior, central and posterior heights. Decrease of the vertebral height ratio; anterior or middle height/posterior or adjacent intact posterior height, by more than 20% of the original value or from above to below 0.80 both appeared to be inhibited during administration of 1α (OH) vitamin D3. Such effect seems to be augmented by simultaneous administration of elcatonin. Actual decrease of vertebral height ratio values and the per cent fall from the original value significantly less in Groups 3 and 4 than in Group 1. Development of vertebral deformity assessed by the changes of the vertebral height thus appears to decrease during treatment with 1α (OH) vitamin D3 especially together with calcitonin in established osteoporosis.  相似文献   
110.
This study was designed to determine the influence of ileal pouch capacity and anal sphincteric function on the clinical outcome after ileal pouch-anal anastomosis. A total of 24 patients who had undergone ileal pouch-anal anastomosis (J pouch) for ulcerative colitis were studied. The 24-hour stool frequency was found to be inversely correlated with the sensitivity threshold volume (STV), maximal tolerance volume (MTV), and distensibility, but was independent of the maximal resting pressure and maximal squeeze pressure. Patients experiencing nocturnal fecal incontinence had maximal resting pressures that were significantly lower than those of nocturnally continent patients. Among the patients with fecal incontinence, those with frequent soiling had lower resting pressures, STV, and distensibility than the patients with intermittent spotting. In addition, the STV in patients needing nocturnal evacuation were lower than those of patients who did not evacuate after falling asleep. The conclusions are as follows. Both stool frequency and the need for nocturnal pouch evacuation correlated directly with pouch volume. Anal incontinence was more common in patients with low internal sphincteric function. In addition, frequent and gross nocturnal incontinent patients demonstrate a worse function in both the anal sphincter and reservoir than those with intermittent spotting.  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