全文获取类型
收费全文 | 52402篇 |
免费 | 4284篇 |
国内免费 | 1584篇 |
专业分类
耳鼻咽喉 | 617篇 |
儿科学 | 634篇 |
妇产科学 | 1110篇 |
基础医学 | 8164篇 |
口腔科学 | 1413篇 |
临床医学 | 4363篇 |
内科学 | 10017篇 |
皮肤病学 | 1001篇 |
神经病学 | 3757篇 |
特种医学 | 1705篇 |
外国民族医学 | 6篇 |
外科学 | 7317篇 |
综合类 | 3969篇 |
现状与发展 | 1篇 |
一般理论 | 5篇 |
预防医学 | 2970篇 |
眼科学 | 1374篇 |
药学 | 4720篇 |
中国医学 | 755篇 |
肿瘤学 | 4372篇 |
出版年
2023年 | 196篇 |
2022年 | 320篇 |
2021年 | 549篇 |
2020年 | 352篇 |
2019年 | 624篇 |
2018年 | 1127篇 |
2017年 | 870篇 |
2016年 | 862篇 |
2015年 | 968篇 |
2014年 | 1283篇 |
2013年 | 1587篇 |
2012年 | 2153篇 |
2011年 | 2084篇 |
2010年 | 1259篇 |
2009年 | 1237篇 |
2008年 | 1855篇 |
2007年 | 1956篇 |
2006年 | 1823篇 |
2005年 | 1497篇 |
2004年 | 1359篇 |
2003年 | 1329篇 |
2002年 | 1259篇 |
2001年 | 4630篇 |
2000年 | 4541篇 |
1999年 | 3905篇 |
1998年 | 1373篇 |
1997年 | 998篇 |
1996年 | 607篇 |
1995年 | 499篇 |
1994年 | 449篇 |
1993年 | 412篇 |
1992年 | 1933篇 |
1991年 | 1676篇 |
1990年 | 1529篇 |
1989年 | 1491篇 |
1988年 | 1297篇 |
1987年 | 1192篇 |
1986年 | 1065篇 |
1985年 | 903篇 |
1984年 | 591篇 |
1983年 | 467篇 |
1982年 | 249篇 |
1981年 | 181篇 |
1980年 | 141篇 |
1979年 | 283篇 |
1978年 | 78篇 |
1974年 | 76篇 |
1973年 | 96篇 |
1972年 | 72篇 |
1969年 | 68篇 |
排序方式: 共有10000条查询结果,搜索用时 11 毫秒
11.
J Parinaud H Grandjean M F Sarramon J M Reme X Monrozies C Sarrazin G Pontonnier 《European journal of obstetrics, gynecology, and reproductive biology》1987,24(4):285-292
In order to ascertain the adequacy of ovarian stimulation protocols with a type of follicular puncture, 126 women undergoing in vitro fertilization received either combination clomiphene/hMG or hMG alone according to a randomized test protocol. Within both groups patients for whom a pelvic examination was required had laparoscopies, while others had transvaginal ultrasonically guided punctures as far as possible. Clomiphene/hMG was more efficient than hMG alone as assessed from the cleavage rate (68% vs. 54%; p less than 0.01) and the pregnancy per attempt rate (16% vs. 5%; p less than 0.05). Laparoscopic punctures were more efficient than ultrasonically guided punctures (mean number of recovered oocytes: 4.8 +/- 2.6 vs. 3 +/- 2.5; p less than 0.001), but slightly better results were achieved by this latter method in ongoing pregnancy per puncture rate (18% vs. 8%; NS). With ultrasonically guided punctures, stimulation by clomiphene/hMG allowed better oocyte recoveries (3.8 +/- 2.5 vs. 2.3 +/- 1.9, p less than 0.05). Such results constitute an argument for preferential use of the clomiphene/hMG stimulation protocol with ultrasonically guided punctures. 相似文献
12.
The effects of intracellular Ca2+ (Ca2+i) on K+ currents in hippocampal cells were examined using acutely isolated cells obtained from adult guinea pigs. Whole-cell voltage-clamp recordings were carried out in a configuration that allowed a continuous perfusion of the intracellular medium. Recording media were made to block inward currents and allowed selective activation of K(+)-dependent outward currents. Voltage-dependent outward currents consisted of an initial rapidly decaying component followed by a sustained component. The time constant of decay of the transient current was about 25 msec, and previous studies (Numann et al., 1987) showed that the kinetic and pharmacological properties of this current closely resembled the A current recorded in invertebrate neurons (Connor and Stevens, 1971; Thompson, 1982). Intracellular perfusion of hippocampal cells with a solution containing elevated Ca2+ (about 4.5 x 10(-4) M) elicited outward currents at the holding potential (-45 to -55 mV) and produced changes in voltage-dependent K+ currents. The transient outward current (IA) activated by depolarization was suppressed with increases in Ca2+i. Delayed, sustained K+ currents were greatly potentiated. Data also showed that, among the 3 effects elicited by Ca2+i, suppression of IA was most sensitive to Ca2+i elevation. Previous results (Numann et al., 1987) showed that IA had a lower threshold (about -45 mV) than sustained currents (about -40 mV). By using low levels of depolarization (-40 mV), IA can be selectively activated, and the suppressive effect of Ca2+i on IA was confirmed on the kinetically isolated IA.(ABSTRACT TRUNCATED AT 250 WORDS) 相似文献
13.
14.
15.
When blood flow through the internal and external carotid arteries is completely interrupted by ipsilateral common carotid artery occlusion, the arterial orbital circulation may be more compromised than the brain supply. We studied a pure and extreme example of this situation in a patient who presented with acute orbital infarction, but no cerebral ischemia on clinical, CT and single-photon emission computerized tomography (SPECT) grounds. Ipsilateral blindness corresponded to retinal, choroidal and optic nerve infarction. The pattern of ophthalmoplegia, with relative sparing of adduction, was more compatible with a muscle than a nerve dysfunction, but a reactive dilated pupil, corneal anesthesia, and orbital pain suggested that the intraorbital branches of the ocular motor nerves and ophthalmic division of the trigeminal nerve were not spared. In addition, signs of widespread ocular ischemia were present. Sequential examinations documented the evolution pattern over 1 year. The absence of an orbital collateral supply from the contralateral external carotid and muscular cervical arteries systems, which contrasted with an adequate middle cerebral artery supply via the contralateral internal carotid artery, may explain this isolated and complete form of orbital ischemia due to common carotid artery occlusion. 相似文献
16.
17.
X Dong M He X Song B Lu Y Yang S Zhang N Zhao L Zhou Y Li X Zhu R Hu 《Diabetic medicine》2007,24(12):1482-1486
AIMS: Our aim was to assess performances of the Cockcroft-Gault and simplified Modification of Diet in Renal Disease (MDRD) formulae in estimating glomerular filtration rate (GFR) in Chinese diabetic populations and their association with vascular risks. METHODS: A total of 1009 patients with Type 2 diabetes were categorized into low estimated GFR groups (GFR < 60 ml/min/1.73 m(2)) and control groups by the two equations. The performances of these formulae were assessed at different stages of kidney function. Carotid artery intima-media thickness (IMT) and the prevalence of diabetic retinopathy or albuminuria were compared among the groups. The ability of these formulae to identify established vascular risk markers using sensitivity, specificity, positive and negative predictive values were also compared. RESULTS: The prevalence of low estimated GFR was 32.7% with the Cockcroft-Gault formula and 5.2% with the MDRD formula, respectively. In low estimated GFR subjects by the MDRD formula, IMT was significantly thicker than those by the Cockcroft-Gault formula (1.2 mm vs. 1.0 mm; P < 0.05), with a higher prevalence of albuminuria (78.4 vs. 52.8%, P < 0.05) and diabetic retinopathy (46.5 vs. 30.5%; P < 0.05). The Cockcroft-Gault formula gave a specificity of 71.7% and a sensitivity of 37.0%, and the MDRD formula gave a specificity of 96.6% and a sensitivity of 7.9% in estimating low GFR relevant for established vascular risks. CONCLUSIONS: These formulae performed differently in Chinese diabetic populations. The simplified MDRD formula is minimally superior to the Cockcroft-Gault formula for its high specificity and positive predictive values in estimating low GFR relevant for vascular risks. 相似文献
18.
The authors reviewed the radiographic manifestations of 17 cases of parosteal osteosarcoma, with pathologic correlation in 15. There were two types of parosteal osteosarcoma radiologically. The majority of cases were type I with uniformly dense masses which had regular borders. They often adhered to the cortex and showed no evidence of soft-tissue invasion which correlated with low-grade pathologic malignancy and a relatively benign clinical course. Type II involved the bone, soft-tissue and the medullary cavity. These lesions were poorly differentiated and frequently accompanied by metastatic lesions.
相似文献
19.
20.
V Pesakova P Gillery F X Maquart J P Borel M Adam 《Biomedicine & Pharmacotherapy》1991,45(10):455-459
The effects of some antirheumatics on the formation and retraction of collagen lattices seeded with fibroblasts have been studied. Among the antirheumatics, diclofenac was the most active inhibitor of lattice retraction, then tropesin and to a lesser extent indomethacin. Ibuprofen which is known as a very slight inhibitor of protein synthesis was able to significantly enhance lattice retraction when 10 micrograms/ml (48.5 microM) and 50 micrograms/ml (242 microM) were used. 相似文献