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   24739篇
  免费   1222篇
  国内免费   137篇
耳鼻咽喉   133篇
儿科学   390篇
妇产科学   254篇
基础医学   3151篇
口腔科学   668篇
临床医学   1661篇
内科学   6074篇
皮肤病学   327篇
神经病学   2025篇
特种医学   1227篇
外科学   4791篇
综合类   108篇
预防医学   626篇
眼科学   510篇
药学   1830篇
中国医学   53篇
肿瘤学   2270篇
  2023年   155篇
  2022年   338篇
  2021年   594篇
  2020年   245篇
  2019年   385篇
  2018年   548篇
  2017年   425篇
  2016年   482篇
  2015年   477篇
  2014年   623篇
  2013年   789篇
  2012年   1219篇
  2011年   1407篇
  2010年   713篇
  2009年   611篇
  2008年   1116篇
  2007年   1250篇
  2006年   1278篇
  2005年   1210篇
  2004年   1120篇
  2003年   1062篇
  2002年   1075篇
  2001年   824篇
  2000年   820篇
  1999年   755篇
  1998年   275篇
  1997年   233篇
  1996年   194篇
  1995年   155篇
  1994年   155篇
  1993年   160篇
  1992年   532篇
  1991年   476篇
  1990年   444篇
  1989年   433篇
  1988年   428篇
  1987年   364篇
  1986年   362篇
  1985年   360篇
  1984年   201篇
  1983年   171篇
  1982年   84篇
  1981年   84篇
  1979年   170篇
  1978年   128篇
  1977年   93篇
  1974年   125篇
  1973年   113篇
  1970年   83篇
  1969年   101篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
To find antiviral agents, various sulfonamidobenzophenone oximes (II) were synthesized from the appropriate m-sulfonamidobenzophenones by hydroxylamine reaction. The reaction products were generally obtained as syn/anti mixtures which were separable by fractional crystallization. The anti isomer had more potent antipoliovirus activity than the syn isomer. Various sulfonamidobenzamides (III) which were structurally related to II were synthesized by the reactions of amino-substituted benzamides with sulfuryl chloride or amines with (aminosulfonyl)benzoyl chloride. Antiviral activity was examined by the plaque-inhibition test. Compounds 5, 36, and 69 exhibited strong antipicornavirus activity. The structure-activity relationships are discussed.  相似文献   
102.
103.
A Usui  K Fujita  M Imaizumi  T Abe  K Inoue  S Matsumoto  K Kato 《Gan no rinsho》1987,33(14):1763-1770
The serum concentrations of both CK-BB and NSE in patients with various lung carcinoma have been determined by the enzyme immunoassay. Serum CK-BB levels were found to be significantly increased (less than 1.0 ng/ml) in patients with a small cell carcinoma (51 cases, 74.5%), adenocarcinoma (77 cases, 36.5%), and a squamous cell carcinoma (68 cases, 39.7%). The serum NSE levels also were increased (less than 6.0 ng/ml) in cases of small cell carcinoma (72.5%), adenocarcinoma (27.3%), and squamous cell carcinoma (26.5%). Since the serum concentrations of bos CK-BB and NSE changed in parallel with the clinical course, they may be useful biomarkers for monitoring the clinical course of patients with lung cancer, especially in cases of small cell carcinoma.  相似文献   
104.
We report herein the cases of two infants who developed right pneumonectomy syndrome, both of whom were born with gross C-type esophageal atresia (EA/TEF), and a hypoplastic right lung arising from the lower esophagus, being a bronchopulmonary foregut malformation (BPFM). Appropriate and well-timed treatments for a variety of sequelae primarily caused by the mediastinal shift must be considered after right pneumonectomy in early childhood.  相似文献   
105.
Are cytokines possible mediators of cancer cachexia?   总被引:1,自引:0,他引:1  
The possible role of cytokines in the development of cancer cachexia was reviewed from the literature. Tumor necrosis factor (TNF)-alpha, interleukin (IL)-1, IL-6, interferon (IFN)-gamma and leukemia inhibitory factor (LIF) can elicit many but not all host changes seen in cancer cachexia, including loss of appetite, loss of body weight, and the induction of acute-phase protein synthesis. However, these cytokines are not always demonstrated in the circulation of the cancer patients. The inability to detect circulating cytokines may be due to their low rate of production, their short half-life and rapid clearance from plasma, or their mode of action (autocrine or paracrine). Different cytokines are induced to stimulate the same response. This is very different from hormonal regulation, where a hormone acts on a cell directly through a specific receptor without depending on other mediators. Specific antibodies including anti-IFN-gamma, anti-TNF and anti-IL-6 antibodies, as well as the cyclooxygenase inhibitor indomethacin, have been used to reverse cancer cachexia. Overlapping physiologic activities make it unlikely that a single substance is the sole cause of cancer cachexia. It is hoped that further investigation on other cytokines and their possible relationships with hormones will help to clarify the mechanisms of cancer cachexia in the near future.This work was supported by a grant from the Japan-Sweden Foundation in 1991.  相似文献   
106.
We report a metastatic pulmonary tumor resected by video-assisted thoracoscopic surgery. A 63-year-old female was found to have four nodules of hepatocellular carcinoma (HCC) in January 1991; after non-surgical treatment, the tumors had become necrotic. In June 1992, a new HCC nodule was found. After infusion chemotherapy, it became necrotic. In September 1993, a solitary lung tumor, 2.4 cm in diameter, appeared at the periphery of the right lung. Because the tumor was considered to be a metastatic HCC rather than a primary lung cancer, it was removed by thoracoscopic wedge resection. Although whether metastasectomy contributes to prolongation of survival is still controversial, thoracoscopic pulmonary resection may be indicated for solitary peripheral metastasis, if the primary HCC is well controlled by multidisciplinary treatment.  相似文献   
107.
A case of renal angiomyolipoma with bone formation is reported. A 61-year-old woman was admitted to our hospital with one month history of fever. About 15 cm in diameter mass was palpated in her right lower abdomen. Plain abdominal roentgenography, ultrasonography and computed tomography showed marked calcification in the cephalic portion of the right kidney, tumors surrounding right kidney and another tumor in the right lower abdomen. All these tumors and the kidney constituted a big mass continuously, and no fatty component was demonstrated. Total excision of the mass including the kidney was performed. The mass was 30 X 24 X 10 cm in size and 3,240 g in weight. Histologically, the tumor was compatible to renal angiomyolipoma. But, radiopaque shadows which looked like calcification were disclosed to be bones, and fatty tissues were not seen so much. Therefore, the name "benign mesenchymoma" was thought to be more acceptable than angiomyolipoma in this case. Preoperative diagnosis of renal angiomyolipoma is the demonstration of fatty densities in the tumor, and the characteristic extrarenal development should also be taken into consideration. Furthermore, the bone formation of angiomyolipoma, which is very rare might be an important finding to angiomyolipoma.  相似文献   
108.
The variations of sublingual temperature, pulse rate, flicker fusion frequency (CFF), subjective fatigue feelings (SFF) and 8 selected reaction times and the relationships between them were examined in six university students under the condition of successive 6-h delayed shift with 8 sleeping h and 22 waking h for 6 d. SFF was measured by the scales proposed by the Japanese Society for Industrial Fatigue Research. On the 2nd d when the shifting was started after the subjects had slept from 00:00 to 08:00 and on the 3rd d after sleeping h of 06:00 to 14:00, the variations of sublingual temperature, pulse rate and CFF showed a pattern of circadian rhythm. However, on the 4th-5th d the rhythms of sublingual temperature and pulse rate were flattened. On the other hand, CFF demonstrated a variation of having a nearly constant tendency till 08:00, followed by a gradual decrease during the daytime. The variation of SFF (the scale of "sleepiness and dullness") was similar to that of CFF, although the change of the score was in the opposite direction. On the 3rd-4th d, the 4th-5th d and the 6th d, significantly high rank correlations were observed between sublingual temperature and pulse rate and between CFF and SFF. However, between sublingual temperature and CFF, a high correlation which was observed on the 1st and the 2nd d was not seen on the 4th-5th and 6th d. Eight selected reaction times were shortened during the experimental days, but there was no consistent pattern of variation within these days. The results of the experiment showed that the relationship between CFF and SFF exists during the daytime when the arousal level is low.  相似文献   
109.
Somatosensory evoked potentials (SEPs) and long loop reflexes (LLRs) to the median nerve stimulation were investigated on 25 normal controls and 25 patients with multiple sclerosis (MS). Fifteen normal controls were also subjected to LLR study by the common peroneal nerve stimulation. The mean height were 159 +/- 8.2 cm in normal controls and 160 +/- 8.9 cm in MS, respectively. LLRs were obtained with 100% reproducibility in all cases. Upper limb LLRs were recorded from m. abductor pollicis brevis by trigger stimulation during isotonic contraction of the thumb, while lower limb LLRs were recorded from m. peroneus longus by trigger stimulation during isotonic eversion of the foot. The threshold of LLR was lower than that of short latency reflex (H-wave) with the mean latency of 40.4 +/- 1.5 ms. The height of subjects revealed an obvious positive correlation not only with the latency of LLR but also with N 20 of SEP, whereas central conduction time was not. Furthermore, a significant correlation was present between the latencies of LLR and N 20, showing a twofold gradient of LLR against N20. There was a significantly prolonged latency difference between H-wave and LLR of lower limb as compared with that of upper limb. When the stimulation site was changed from the wrist to the elbow, the latency difference between M-wave and H-wave shortened. This fact, therefore, appears to be against "resonance hypothesis" that LLR is set off according to the intrinsic mechanical oscillation given to the muscle concerned.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   
110.
The binding of twelve structurally related sulfonamides to serum albumins including human was investigated using a circular dichroic technique. Some differences of circular dichroic spectral characteristics were observed when sulfonamides were bound to the same albumin or when the drug was bound to several albumins. The differences in these circular dichroic characteristics may be due to various asymmetries. The Scatchard plots indicated that only the primary site was capable of inducing ellipticities of the drugs. The interaction with rabbit serum albumin showed significantly large binding constants and apparent anisotropy factors (g′, values), in comparison with other albumins. No significant correlation between the g′ values of the induced circular dichroic bands and partition coefficients or/and pKa values was observed. The induced ellipticities of the drug-albumin complexes decreased with pH. This pH dependence can be explained by the ionization of drug and albumin as well as the conformational change of the albumin.  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