全文获取类型
收费全文 | 1107744篇 |
免费 | 84829篇 |
国内免费 | 2836篇 |
专业分类
耳鼻咽喉 | 13996篇 |
儿科学 | 37508篇 |
妇产科学 | 30703篇 |
基础医学 | 162393篇 |
口腔科学 | 30782篇 |
临床医学 | 100000篇 |
内科学 | 215941篇 |
皮肤病学 | 24752篇 |
神经病学 | 90149篇 |
特种医学 | 43261篇 |
外国民族医学 | 313篇 |
外科学 | 163791篇 |
综合类 | 24201篇 |
现状与发展 | 1篇 |
一般理论 | 486篇 |
预防医学 | 90463篇 |
眼科学 | 24470篇 |
药学 | 78387篇 |
3篇 | |
中国医学 | 2246篇 |
肿瘤学 | 61563篇 |
出版年
2021年 | 8902篇 |
2019年 | 9285篇 |
2018年 | 12996篇 |
2017年 | 10277篇 |
2016年 | 11709篇 |
2015年 | 13186篇 |
2014年 | 17893篇 |
2013年 | 26452篇 |
2012年 | 35962篇 |
2011年 | 37768篇 |
2010年 | 22187篇 |
2009年 | 21232篇 |
2008年 | 34763篇 |
2007年 | 36618篇 |
2006年 | 36810篇 |
2005年 | 35217篇 |
2004年 | 33631篇 |
2003年 | 32248篇 |
2002年 | 30823篇 |
2001年 | 50382篇 |
2000年 | 51447篇 |
1999年 | 43340篇 |
1998年 | 12530篇 |
1997年 | 11208篇 |
1996年 | 11258篇 |
1995年 | 10723篇 |
1994年 | 9960篇 |
1993年 | 9241篇 |
1992年 | 34378篇 |
1991年 | 33428篇 |
1990年 | 32823篇 |
1989年 | 31642篇 |
1988年 | 28766篇 |
1987年 | 28720篇 |
1986年 | 26774篇 |
1985年 | 25889篇 |
1984年 | 19309篇 |
1983年 | 16310篇 |
1982年 | 9716篇 |
1979年 | 17599篇 |
1978年 | 12666篇 |
1977年 | 10683篇 |
1976年 | 10036篇 |
1975年 | 10472篇 |
1974年 | 12674篇 |
1973年 | 12206篇 |
1972年 | 11206篇 |
1971年 | 10425篇 |
1970年 | 9635篇 |
1969年 | 8960篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
A number of neurotransmitters and neuropeptides in the hypothalamus play a role in the control of food intake, metabolism, and body weight. Particularly, noradrenergic mechanisms in several areas of the hypothalamus are involved. Control of peripheral metabolism by the hypothalamus is achieved via autonomic modulation of the function of hepatocytes, adipocytes, and the endocrine cells in the islets of Langerhans. The autonomic control mechanisms ultimately lead to an appropriate shaping of blood glucose, plasma FFA, and insulin profiles to guarantee an adequate flow of nutrients under different physiological situations. Peripheral insulin and glucose can penetrate into the brain where they might affect the function of those brain structures involved in control of food intake, metabolism, and body weight. 相似文献
992.
B T Hyman J E Flory S E Arnold G W Van Hoesen R L Schelper H Ghanbari H Haigler 《Journal of geriatric psychiatry and neurology》1991,4(4):231-235
A quantitative assay for ALZ-50 immunoreactivity was evaluated in samples of superior temporal gyrus taken at autopsy from 13 Alzheimer patients and 11 controls. The assayable immunoreactivity appears to be stable for at least 24 hours postmortem but was lost with formalin fixation. The mean value of the Alzheimer patients was tenfold higher than that of the controls (P less than .002). The values of four Alzheimer samples overlapped with the low levels seen in controls, but no controls had elevated levels. In this sample population, therefore, the assay had a sensitivity of 69% and specificity of 100%. 相似文献
993.
B J Pugh 《Nurse educator》1991,16(3):5-6
This series of articles, Managing Your Academic Career, presents ways to intentionally improve your teaching. This first article explains the concept of becoming an intention teacher. Subsequent articles will deal with strategies that are useful in clinical teaching, such as preparing students to value and use research in practice, and providing feedback to students in the clinical setting. 相似文献
994.
995.
Single or combined monoclonal antibodies (McAbs) Zh53, Zh820, and Zh2-1 have been used to eliminate malignant clonogenic cells from human bone marrow. The test of cytotoxicity showed that all of these McAbs could express high specific cytotoxic action against HL-60 cells and were selectively complement-dependent cytotoxic to various types of fresh leukemic cells. Clonogenic assay detected that single treatment with antibody and rabbit complement (RC) could reduce clonogenic units of HL-60 cells by more than 2 logs and two treatments reduced clonogenic units by more than 4 logs. However, combination of 2 McAbs could reduce clonogenic units by 4-5 logs. The data suggest that multiple treatments with McAbs and RC or a combination of 2 McAbs are more effective than a single treatment in eliminating clonogenic tumor cells. Treatment of normal human bone marrow with Zh53, Zh2-1 and RC did not produce a loss of normal CFU-GM, but treatment with Zh820 reduced the clonic units of normal CFU-GM by 24%.
相似文献
996.
997.
We studied the relationship between arterial carbon dioxide tension (PaCO2) and fresh gas flow (FGF) during use of the Bain breathing circuit for Caesarean section anaesthesia. Thirty-one patients undergoing Caesarean section were anaesthetised using the Bain circuit with intermittent positive pressure ventilation. The PaCO2 were measured at FGF of 70 ml X kg-1 X min-1, 80 ml X kg-1 X min-1, and 100 ml X kg-1 X min-1. The FGF requirement to maintain a given PaCO2 during Caesarean section anaesthesia is the same as the requirements for nonpregnant subjects, despite the increase in carbon dioxide production associated with pregnancy. This is probably because the total FGF determined by body weight and given during Caesarean section anaesthesia is 15-20 per cent higher than nonpregnant levels, due to the weight gain associated with pregnancy. A FGF of 100 ml X kg-1 of pregnant weight/min maintains PaCO2 of 4.44 kPa predelivery, which is in the desirable range of PaCO2 during Caesarean section. 相似文献
998.
B Dahlstr?m 《International anesthesiology clinics》1986,24(2):29-42
Spinal opiate analgesia has opened an exciting new field of research and has also rapidly gained widespread clinical acceptance. This mode of administration has obvious and definite advantages over conventional pain therapy; however, the field is still at an early stage of development. More research is clearly needed to provide methods for coping with some of the drawbacks of this method of pain relief. Important areas for future research include (1) the CSF kinetics of opiates; (2) the physiological mechanisms underlying the rostral spread of drugs within the CSF compartment; (3) a search for safer and more selective drugs; and (4) an evaluation of the extent to which pain-modulating systems at different levels in the CNS can be regulated by opiates and drugs interfering with other neurotransmitters. In this context it is essential to emphasize the importance of simultaneous study of the pharmacokinetics and the pharmacodynamic/clinical effects in providing a rational basis for a better understanding of the mechanisms of actions underlying spinal opiate analgesia. 相似文献
999.
We report 2 cases of diffuse intraperitoneal metastases from testicular carcinoma following transabdominal retroperitoneal lymphadenectomy. This is an unusual pattern of metastasis for nonseminomatous germ cell tumors and it is believed to be the result of direct seeding from lymphatic leakage secondary to surgery. The value of computerized tomography in diagnosing this entity is emphasized. 相似文献
1000.
The averaged evoked compound action potentials (AECAPs) were recorded from the ipsilateral pyramidal tract of awake, unrestrained cats before, during, and after continuous electrical stimulation of the cerebral cortex via chronically implanted activated iridium or platinum-30% iridium (Pt30%Ir) microelectrodes. After stimulating 24 h at 20 pulses per second (pps), using charge-balanced, 200-microseconds pulse pairs of 40 to 80 microA (400 to 800 microC/cm2, 8 to 16 nC/phase (ph), 2 to 4 A/cm2), there was a transient elevation of the threshold of the early (direct) and of the alte (transynaptic) components of the AECAP. After cessation of continuous stimulation at 80 microA, the threshold of the early component of the AECAP remained elevated for as long as 24 h and the late component as long as 4 days, indicating significant but reversible depression of the electrical excitability of cortical neurons close to the microelectrodes. In three cats stimulated 23 h/day for 1 week, the AECAP also recovered to their prestimulus threshold. In contrast, pulsing for 24 h at 320 microA (3200 microC/cm2, 64 nC/ph, 16 A/cm2) produced marked elevation of the threshold of the AECAPs which was not reversed by 7 to 12 days after termination of intracortical stimulation. The electrical excitability of neurons adjacent to (unpulsed) microelectrodes 2 mm from the pulsed electrode was not affected. The observations reported here, in conjunction with the histologic results reported in the companion paper, indicate that both the Pt30%Ir and the iridium microelectrodes can be operated safely at currents to at least 80 microA, charge/ph of 16 A/cm2, and a charge density of 800 microC/cm2 X ph. However, on the basis of the electrophysiologic criteria, both types appear to be unsafe when pulsed at 320 microA (64 nC/ph, 3200 microC/cm2 X ph, 16 A/cm2). 相似文献