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   7459篇
  免费   338篇
  国内免费   63篇
耳鼻咽喉   91篇
儿科学   141篇
妇产科学   65篇
基础医学   1056篇
口腔科学   156篇
临床医学   450篇
内科学   2084篇
皮肤病学   154篇
神经病学   563篇
特种医学   343篇
外科学   1220篇
综合类   17篇
预防医学   192篇
眼科学   115篇
药学   399篇
中国医学   23篇
肿瘤学   791篇
  2023年   51篇
  2022年   76篇
  2021年   131篇
  2020年   60篇
  2019年   105篇
  2018年   130篇
  2017年   112篇
  2016年   121篇
  2015年   173篇
  2014年   216篇
  2013年   291篇
  2012年   391篇
  2011年   406篇
  2010年   223篇
  2009年   221篇
  2008年   375篇
  2007年   459篇
  2006年   475篇
  2005年   419篇
  2004年   478篇
  2003年   441篇
  2002年   508篇
  2001年   133篇
  2000年   131篇
  1999年   146篇
  1998年   111篇
  1997年   110篇
  1996年   96篇
  1995年   87篇
  1994年   90篇
  1993年   81篇
  1992年   112篇
  1991年   91篇
  1990年   80篇
  1989年   77篇
  1988年   67篇
  1987年   62篇
  1986年   51篇
  1985年   52篇
  1984年   38篇
  1983年   39篇
  1982年   31篇
  1981年   38篇
  1980年   23篇
  1979年   28篇
  1978年   31篇
  1977年   24篇
  1976年   23篇
  1975年   24篇
  1973年   20篇
排序方式: 共有7860条查询结果,搜索用时 108 毫秒
61.
The effects of butorphanol injection on baroreflex control of heart rate were investigated using both pressor and depressor tests in eighteen adult patients. Baroreflex sensistivity was attenuated after butorphanol injection in the pressor test using phenylephrine, whereas it was unchanged in the depressor test using nitroglycerine. No resetting of the baroreflex occurred after butorphanol injection. After the administration of butorphanol, plasma epinephrine and norepinephrine levels increased. These results suggest that it is safe to use butorphanol clinically even when a reduction in blood pressure due to hypovolemia or unclamping of the major artery is expected and that it is disadvantageous to administer the drug when an increase in blood pressure due to cross-clamping of the major artery is predicted.(Wajima Z, Inoue T and Ogawa R: The effects of butorphanol on baroreflex control of heart rate in man. J Anesth 7: 411--418, 1993)  相似文献   
62.
We examined anti-gelatin IgG in sera of children who suffered from systemic adverse reactions upon immunization with gelatin-containing live virus vaccines. In the group of 30 children who had immediate-type reactions and anti-gelatin IgE, 30 (100%) had anti-gelatin IgG and 29 (96%) had anti-gelatin IgG4. In another group of 75 children who had nonimmediate-type reactions and no anti-gelatin IgE, 22 (29%) had anti-gelatin IgG and six (8%) had IgG4. The IgG positivity well correlated with the lymphocyte proliferation assay positivity. In contrast, as a negative control, all 24 children who had no allergic reaction to live virus vaccines had no anti-gelatin IgG and IgG4. The results suggest that immune-response to gelatin may play a role in the pathogenesis of systemic nonimmediate-type reactions to the live virus vaccines.  相似文献   
63.
Purpose. Indomethacin is well known to be metabolized via O-demethylation and N-deacylation. In this paper we found an enzyme involved in the hydrolysis of amide-linkage of indomethacin and partially characterized it as well as its substrate specificity. Methods. An indomethacin hydrolyzing enzyme was purified to homogeneity from pig liver microsomes using columns of Q-Sepharose, Red-Sepharose and Blue-Sepharose. The enzyme activity was assayed by measuring of -chlorobenzoic acid liberated from indomethacin by HPLC. Results. The purified enzyme effectively hydrolyzed the amide linkage in indomethacin but not those in -naphthylacetate and -nitrophenylacetate, which are typical substrates for carboxylesterase. The subunit molecular mass of the enzyme was 65 kDa according SDS-polyacrylamide gel electrophoresis. The Michaelis constant (Km) and maximum velocity (Vmax) values for indomethacin were 67.8 µM and 9.02 nmol/min/mg protein, respectively. The amino acid sequence analysis of the enzyme after cyanogen bromide cleavage showed high homology with a mouse carboxylesterase isozyme designated as ES-male. The activity of indomethacin hydrolysis was relatively high in the pig, rabbit and human liver homogenate, but not in those from rat and mouse. On the other hand, purified human liver carboxylesterases pl 5.3 and 4.5, and pig liver carboxylesterases have no catalytic activity for indomethacin. Conclusions. These results indicate that the hydrolysis of amide-linkage of indomethacin in humans would be associated with an enzyme similar to the indomethacin hydrolyzing enzyme from pig liver microsomes described here.  相似文献   
64.

Purpose

The purpose of this study was to determine the effect of increasing the concentrations of sévoflurane anaesthesia on the distribution of diaphragm blood flow (Qdi) in ten dogs during mechanical ventilation.

Methods

Animals were divided into two groups, sévoflurane (n = 6) and time control (n = 4) groups. Blood flow to the crural and the costal diaphragm (Qcru, Qcost) was determined by the hydrogen clearance technique at 0, 0.5, 1.0 and 1.5 minimum alveolar concentration (MAC) of sévoflurane after a 30 min period of steady-state conditions. Cardiac output (CO) and the mean arterial blood pressure (MBP) were also measured.

Results

Sevoflurane anaesthesia caused a reduction in CO (L · min?1) from a control value of 1.51 ± 0.21 to 1.38 ±0.1 (0.5 MAC), 1.09 ± 0.15 (1.0 MAC) and 0.98 ± 0.12 (1.5 MAC) (Mean ± SD). Mean blood pressure, Qcru and Qcost also decreased with increasing depth of anaesthesia. In addition, the decrease of Qcru was greater than that of Qcost at all levels of MBP and CO. No change occurred in these variables in the lime control group.

Conclusion

Sevoflurane anaesthesia changes the distribution of Qdi with a greater reduction occurring in Qcru than in Qcost.  相似文献   
65.
We report herein the rare case of a 79-year-old man who suffered permanent paraplegia after undergoing an otherwise successful total arch replacement for a ruptured aortic arch aneurysm. During cardiopulmonary bypass, perfusion to the distal aorta was maintained from the femoral artery, and postoperative aortography showed intact tributaries from the aorta including the intercostal arteries. Postoperative paraplegia is an extremely rare complication of operations on the aortic arch; however, we speculate that the paraplegia in this patient could be attributed either to a steal phenomenon involving the radicular artery, or to the anatomical particularity of the spinal cord artery described by Cole and Gutelius as the segmental system.  相似文献   
66.
We encountered eight rare cases of myonephropathic metabolic syndrome (MNMS) which developed as a complication of the femoral arterial cannulation (FAC) during cardiopulmonary bypass (CPB). Seven were boys ranging in age from 4–17 years, and all had undergone open heart surgery using CPB with a hemodilution technique. These eight corresponded to 1.9 per cent of the 420 patients treated with CPB before June, 1974. The pump priming fluid used was either Ringer’s lactate solution alone or that containing a small amount of colloidal solution. Duration of CPB ranged from 52 min to 2 hrs and 42 min, but the FAC period was more than 3 hrs in each case. Acute renal failure occurred in 3 and 2 required peritoneal dialysis. Severe respiratory insufficiency occurred in 2 and one died 3 months after the operation. The most effective means to prevent the development of MNMS seems to be the local cooling of the cannulated limb during FAC. MNMS did not occur in 444 cases of CPB with FAC after July 1974, and here local cooling was applied in all cases.  相似文献   
67.
The pattern of subchondral bone density has been considered to reflect the stress distribution that occurs under physiologic loading conditions. To determine the force distribution through the wrist joint with Kienb?ck's disease in living subjects, we applied a computed tomography osteoabsorptiometry and investigated the subchondral bone density pattern across the radio-carpal joint of 6 normal subjects and 10 patients suffering from Kienb?ck's disease (Lichtman's stage IIIA, 5 patients; stage IIIB, 5 patients). A single density maximum was found in each scaphoid and lunate fossa in all normal subjects. Among the subjects with Kienb?ck's disease, the current analysis demonstrated that the density maximum area significantly increased in the scaphoid fossa and decreased in the lunate fossa from stage IIIA to IIIB group. These findings indicate that the load is shifted away from the lunate to the scaphoid with the progression of Kienb?ck's disease in living subjects.  相似文献   
68.
We herein describe thallium-201 single photon emission tomography (T1-201 SPECT) findings in three cases with intracranial angioma. One of the lesions which was associated with chronic encapsulated intracerebral hematoma showed moderate accumulation of T1-201, but, others demonstrated no accumulation. The usefulness and limitations of T1-201 SPECT in differential diagnosis of intracranial mass lesions are discussed.  相似文献   
69.
Summary  Objective. We first applied a novel haemostatic strategy involving Argon Plasma Coagulation (APC), an innovative no-touch electrocoagulation technique in which a high-frequency alternating current is delivered to the tissue through ionized argon gas, to brain tumour surgery, and report its usefulness and limitations.  Methods. The APC system we used comprised an APC 300 developed by ERBE Elektromedizin GmbH, Germany. We applied APC to 13 brain tumours in 12 patients (5 meningiomas, 4 sarcomas, 2 glioblastomas, and 2 pituitary adenomas). To avoid unnecessary thermal injury to the tissue as much as possible, power/gas flow settings of 20 and 40 W were used. The impact time was varied individually but was around several seconds per one impact. The argon jet (1.5–4.5 L/min) clears a field of pooled blood and evenly conducts electrical energy to the target tissue. A thin and flexible probe particularly increased the usefulness of APC for haemostasis on deep-seated skull base tumour operations under a microscope.  Conclusion. All patients were successfully treated and satisfied with the surgical results without any complications due to APC. APC appears to be an excellent alternative strategy for achieving haemostasis on vascular-rich brain tumour surgery, and may be valuable for the management of patients with coagulation defects.  相似文献   
70.
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