全文获取类型
收费全文 | 19478篇 |
免费 | 1196篇 |
国内免费 | 511篇 |
专业分类
耳鼻咽喉 | 290篇 |
儿科学 | 200篇 |
妇产科学 | 238篇 |
基础医学 | 1445篇 |
口腔科学 | 1166篇 |
临床医学 | 2050篇 |
内科学 | 1780篇 |
皮肤病学 | 540篇 |
神经病学 | 1085篇 |
特种医学 | 1029篇 |
外国民族医学 | 2篇 |
外科学 | 4578篇 |
综合类 | 2707篇 |
预防医学 | 1005篇 |
眼科学 | 373篇 |
药学 | 1311篇 |
15篇 | |
中国医学 | 849篇 |
肿瘤学 | 522篇 |
出版年
2024年 | 52篇 |
2023年 | 322篇 |
2022年 | 644篇 |
2021年 | 769篇 |
2020年 | 657篇 |
2019年 | 596篇 |
2018年 | 574篇 |
2017年 | 572篇 |
2016年 | 600篇 |
2015年 | 601篇 |
2014年 | 1082篇 |
2013年 | 1117篇 |
2012年 | 936篇 |
2011年 | 1177篇 |
2010年 | 1104篇 |
2009年 | 886篇 |
2008年 | 920篇 |
2007年 | 957篇 |
2006年 | 851篇 |
2005年 | 777篇 |
2004年 | 648篇 |
2003年 | 569篇 |
2002年 | 446篇 |
2001年 | 361篇 |
2000年 | 346篇 |
1999年 | 324篇 |
1998年 | 319篇 |
1997年 | 284篇 |
1996年 | 244篇 |
1995年 | 265篇 |
1994年 | 243篇 |
1993年 | 215篇 |
1992年 | 171篇 |
1991年 | 195篇 |
1990年 | 161篇 |
1989年 | 135篇 |
1988年 | 138篇 |
1987年 | 117篇 |
1986年 | 111篇 |
1985年 | 113篇 |
1984年 | 105篇 |
1983年 | 66篇 |
1982年 | 107篇 |
1981年 | 58篇 |
1980年 | 70篇 |
1979年 | 37篇 |
1978年 | 34篇 |
1977年 | 32篇 |
1976年 | 25篇 |
1974年 | 17篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
71.
72.
We determined the microviscosity of synaptosomal plasma membrane vesicles (SPMV) isolated from bovine cerebral cortex and
liposomes of total lipids (SPMTL) and phospholipids (SPMPL) extracted from SPMV. Changes in the microviscosity induced by
the range and rate of lateral diffusion were measured by the intramolecular excimerization of 1,3-di(1-pyrenyl)-propane (Py-3-Py).
The microviscosity values of the direct probe environment in SPMV, SPMTL and SPMPL were 38.17, 31.11 and 27.64 cP, respectively,
at 37°C and the activation energies (Ea) of the excimer formation of Py-3-Py in SPMV, SPMTL and SPMPL were 8.236, 7.448 amd 7.025 kcal/mol, respectively. Probe location
was measured by polarity and polarizability parameters of the probe Py-3-Py and probe analogues, pyrene, 1-pyrenenonanol and
1-pyrenemethyl-3β-hydroxy-22,23-bisnor-5-cholenate (PMC), incorporated into membranes or solubilized in reference solvents.
There existed a good linear relationship between the first absorption peak of the1La band and the polarizability parameter (n
2−1)/(2n
2+1). The calculated refractive index values for SPMV, SPMTL and SPMPL were close to 1.50, which is higher than that of liquid
paraffin (n=1.475). The probe location was also determined by using a polarity parameter (f−1/2f1). Here f=(ε−1)/(2ε+1) is the dielectric constant function and f'=(n
2−1)/(2n
2+1) is the refractive index function. A correlation existed between the monomer fluorescence intensity ratio and the solvent
polarity parameter. The probes incorporated in SPMV, SPMTL, and SPMPL report a polarity value close to that of 1-hexanol (ε=13.29).
In conclusion, Py-3-Py is located completely inside the membrane, not in the very hydrophobic core, but displaced toward the
polar head groups of phospholipid molecules, e.g., central methylene region of aliphatic chains of phospholipid molecules. 相似文献
73.
An immunohistochemical study using the mirror-image technique was performed in order to establish whether amyloid P component is involved in the mechanism of deposition of amyloid fibrils in senile plaques (SPs) in Alzheimer-type dementia (ATD). Ninety percent of /A4 protein-immunoreactive SPs were also stained by the anti-amyloid P component immunchistochemistry, and this applied to all of the diffuse, primitive and classical types of /A4 deposits. These findings may suggest an involvement of amyloid P component in the formation of amyloid fibrils in senile plaques in ATD brains. 相似文献
74.
Hakan Özkardeş Cankon Germiyanoğlu Ümit Kurt Levent Peşkircioğlu Uğur Altuğ Demokan Erol 《Pediatric surgery international》1995,10(7):488-491
Between 1983 and 1993, 41 patients underwent a first-stage Belt-Fuqua operation for penile hypospadias repair and 39 completed the second stage. Minor complications were observed after the first stage. The primary success rate following the second stage was 82%. Major complications noted after the second stage consisted mainly of fistula formation. The surgical technique is described and alternative methods are discussed. 相似文献
75.
A. C. M. Schrikker H. Wesenhagen S. C. M. Luijendijk 《Pflügers Archiv : European journal of physiology》1995,430(5):862-870
In this study we have investigated the effects of breath holding and of the physical properties of gases on four different respiratory dead spaces (V
D): the Fowler, the physiological, the washout and the inert gas dead space. The experiments were performed with dogs which were ventilated artifically with breathing patterns with different post-inspiratory breath holding times (t
a) of 0, 0.5, 1.0 and 2.0 s. Tracer amounts of acetone, ether and enflurane were infused continuously into a peripheral vein and a bolus of a mixture of krypton, Freon12 and SF6 was introduced into the peritoneal cavity. After reaching steady state, samples of arterial blood, mixed venous blood and mixed expired air were taken simultaneously. From the partial pressures (P
a, P
¯V and P
respectively) we determined the excretion (=P/P¯V), retention (R=Pa/P¯V) and the physiological dead space fraction (V
D,phys/V
T=(1 P/Pa) for each gas, where V
T is tidal volume. Further, we recorded the expirograms of the six tracer gases and of CO2 from which the Fowler dead space fractions (V
D,Fowler/V
T) of the different gases were determined. Also the washout dead space fractions (V
D,washout/V
T) for He and SF6 were determined as well as the inert gas dead space fraction (V
D,MIGET/V
T) with the use of the multiple inert gas elimination technique (MIGET).With the exception of V
D,phys/V
T for SF6, all dead space fractions decreased with increasing t
a. V
D,phys/V
T for the poorly soluble gas SF6 was considerably larger than V
D,phys/V
T for the remaining gases. For the highly soluble acetone V
Fowler/V
T was considerably smaller than V
D,Fowler/V
T for the other gases. V
D,washout,SF6/V
T was always larger than V
D,washout,He/V
T and V
D,Fowler,SF6/V
T. Further, V
D,phys/V
T was larger than V
D,Fowler/V
T for SF6 and acetone. However, for gases with intermediate solubility in blood V
D,phys/V
T tended to be smaller than V
D,Fowler/V
T. We conclude that the respiratory dead spaces are affected by the breathing pattern and by the physical properties of gases, i.e. their diffusivity in alveolar gas and their solubility in blood or lung tissue. 相似文献
76.
Since its conception, several techniques have been described for laparoscopic appendicectomy. We describe a technique which utilizes a 5-mm bipolar forceps designed to coagulate and cut tissues at the same time; 50 pediatric patients underwent laparoscopic appendicectomy for acute appendicitis using this stripping and teasing technique. No bleeding complications occurred. There were only two postoperative abscesses in the series. We believe that the bipolar laparoscopic striptease appendicectomy technique as developed by the senior author is safe, quick, and effective, even for severe appendicitis. 相似文献
77.
78.
79.
Mega-Liposuction: Analysis of 1520 Patients 总被引:1,自引:0,他引:1
Ali Eed MD 《Aesthetic plastic surgery》1999,23(1):16-22
Fifteen hundred and twenty cases of liposuction/liposculpture were performed at Dr. M. Erfan & Bagedo Hospitals and King
Abdulaziz University Hospital in Jeddah from January 1983 to December 1994. These cases were mostly females. The age group
was from 16–65 years. Multiple procedures were performed in 11.68% of these cases. The change in hemoglobin and the hematocrit
ratio pre- and post-operatively, and the incidence of complications, were studied. The percentage of surface area operated
upon rather than the amount of fat removed was the most important relevant factor. 相似文献
80.
Comparison of ultrasound transmission velocity with computed metacarpal radiogrammetry and dual-photon absorptiometry 总被引:2,自引:0,他引:2
A. Sili Scavalli M. Marini A. Spadaro V. Riccieri A. Cremona A. Zoppini 《European radiology》1996,6(2):192-195
The aim of our study was to evaluate the validity of a quantitative US technique for measuring the bone density of the proximal phalanges of the nondominant hand compared with computed metacarpal radiogrammetry and dual-photon absorptiometry (DPA) of the lumbar spine. Mean US bone velocity (UBV) correlated with mean metacarpal cortical index (MCI), with mean metacarpal bone density (MBD) and with bone mineral density (BMD) of the lumbar spine, whereas it was correlated negatively with age and menopause duration. The average UBV was significantly higher in premenopausal women than in postmenopausal women, and higher in normal lumbar DPA patients than in reduced lumbar DPA patients. We conclude that the US evaluation of the nondominant hand proximal phalanges may be a new alternative way for measuring bone mass in screening of osteoporosis.
Correspondence to: A. Sili Scavalli 相似文献