全文获取类型
收费全文 | 339899篇 |
免费 | 28169篇 |
国内免费 | 12903篇 |
专业分类
耳鼻咽喉 | 3876篇 |
儿科学 | 4938篇 |
妇产科学 | 6019篇 |
基础医学 | 45336篇 |
口腔科学 | 6519篇 |
临床医学 | 38877篇 |
内科学 | 56682篇 |
皮肤病学 | 6455篇 |
神经病学 | 21312篇 |
特种医学 | 14630篇 |
外国民族医学 | 97篇 |
外科学 | 40011篇 |
综合类 | 31676篇 |
现状与发展 | 43篇 |
一般理论 | 102篇 |
预防医学 | 21896篇 |
眼科学 | 9127篇 |
药学 | 33147篇 |
189篇 | |
中国医学 | 12467篇 |
肿瘤学 | 27572篇 |
出版年
2024年 | 821篇 |
2023年 | 3933篇 |
2022年 | 10423篇 |
2021年 | 14404篇 |
2020年 | 9769篇 |
2019年 | 9776篇 |
2018年 | 10921篇 |
2017年 | 9244篇 |
2016年 | 9804篇 |
2015年 | 14219篇 |
2014年 | 17431篇 |
2013年 | 18005篇 |
2012年 | 26602篇 |
2011年 | 27384篇 |
2010年 | 16967篇 |
2009年 | 13560篇 |
2008年 | 19168篇 |
2007年 | 18432篇 |
2006年 | 17348篇 |
2005年 | 16683篇 |
2004年 | 12674篇 |
2003年 | 11214篇 |
2002年 | 9544篇 |
2001年 | 7852篇 |
2000年 | 7710篇 |
1999年 | 7023篇 |
1998年 | 3579篇 |
1997年 | 3319篇 |
1996年 | 2717篇 |
1995年 | 2577篇 |
1994年 | 2251篇 |
1993年 | 1547篇 |
1992年 | 2809篇 |
1991年 | 2655篇 |
1990年 | 2235篇 |
1989年 | 2073篇 |
1988年 | 1900篇 |
1987年 | 1649篇 |
1986年 | 1471篇 |
1985年 | 1282篇 |
1984年 | 837篇 |
1983年 | 725篇 |
1982年 | 491篇 |
1981年 | 500篇 |
1980年 | 418篇 |
1979年 | 629篇 |
1978年 | 459篇 |
1977年 | 436篇 |
1976年 | 382篇 |
1974年 | 403篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
991.
E. W. Brien Joseph M. Mirra Steven Kessler M. Suen J. K. S. Ho W. T. Yang 《Skeletal radiology》1997,26(4):246-255
It is not uncommon for sarcomatous transformation of giant cell tumor (GCT) of bone to occur after radiation, but rarely
does malignant transformation occur spontaneously, with less than 15 cases reported up to 1995. Only four of these cases have
been documented in detail. We report two additional cases of GCT of bone spontaneously transforming or ”dedifferentiating”
into osteosarcoma without radiation therapy. The first case is absolutely unique and most interesting in that the dedifferentiation
process occurred in one of multiple GCT lung metastases 6 years after successful eradication of a primary tibial tumor. The
right lung was resected due to development of a large tumor, and at pathologic examination, demonstrated several small nodules
of conventional GCT and a much larger, 14-cm mass composed of a mixture of GCT and high-grade osteosarcoma. The second case
involved a physician, who had a large tumor in the sacrum with vague symptoms for 8 years. Open biopsy revealed conventional,
benign GCT of bone with a secondary aneurysmal bone cyst. Complete curettage 2 weeks later revealed, in addition to areas
of conventional, benign GCT a second component of very high grade osteosarcoma. Both patients died less than 1.5 years from
diagnosis. This report of osteosarcomatous transformation of a conventional GCT of bone strengthens the theory that there
is a mesenchymal cell line in GCT that may spontaneously tansform to sarcoma. 相似文献
992.
993.
Conventionally a confidence interval (CI) for the standardized mortality ratio is set using the conservative CI for a Poisson expectation, μ. Employing the mid-P argument we present alternative CIs that are shorter than the conventional ones. The mid-P intervals do not guarantee the nominal confidence level, but the true coverage probability is only lower than the nominal level for a few short ranges of μ. The implications for mid-P confidence intervals of various proposed definitions of two-sided tests for discrete data are discussed. 相似文献
994.
Z Z Yang 《中华结核和呼吸杂志》1992,15(2):72-4, 125
The technique of Enzyme linked immuno-electrophoresis (ELIEP) was established to detect the specific antibody against tubercle bacilli. The results of 730 cases showed that the sensitivity of this method is 97.33%, and the specificity, 97.5%. Thus this method is more sensitive than the ELISA methods which had bean published. The manipulation of ELIEP is simple, convenient, and fast, reagent stable. This method may be used in diagnosis of tuberculosis with reliability and efficiency. 相似文献
995.
The biomechanical effects of disc injury on flexion-extension were investigated in nine fresh porcine functional spinal units. Under 12 N-m in extension and 6 N-m in flexion, the range of motion among intact specimens were 23.11 degrees -33.29 degrees (mean = 26.07 degrees , SD = 3.25 degrees ), which shifted to 28.04 degrees -38.46 degrees (mean = 31.69 degrees , SD = 3.50 degrees ) when discs were injured. Similarly, the neutral zones among intact and disc injured specimens were 4.88 degrees -12.75 degrees (mean = 9.32 degrees , SD = 2.60 degrees ) and 9.50 degrees -24.43 degrees (mean = 16.80 degrees , SD = 4.69 degrees ) respectively. To obviate the differences between tested specimens, the changes of neutral zone and the range of motion after disc injury were normalized and expressed as ratios as compared to the same items before disc injury. The neutral zone ratio ranged from 1.29 to 3.18 (mean = 1.87, SD = 0.55, p < 0.01). For range of motion, it ranged from 1.13 to 1.42 (mean = 1.22, SD = 0.09, p < 0.01). The change of flexibility coefficient, however, was statistically insignificant in either flexion or extension. The model presented defines the range of motion, the neutral zone as well as the flexibility coefficient under a specific load. It suggests that major spinal instability can be elicited by a minimum flexion-extension moment, as reflected by a profound change of the neutral zone, after disc injury. 相似文献
996.
Taurine has been proposed as an inhibitory neurotransmitter or neuromodulator in the vertebrate central nervous system. Within the spinal cord, taurine has been shown to have a direct inhibitory effect on spinal neurons and to have a selective antinociceptive effect on chemically induced nociception. Although sufficient data exists to suggest that taurine plays a neurotransmitter or neuromodulatory role in the spinal cord, it is not known whether this amino acid is present in axon terminals nor if this amino acid has a unique pattern of distribution within spinal tissue. To address these questions a monoclonal antibody against taurine was employed to localize taurine-like immunoreactivity in the dorsal horn of the rat spinal cord by using both light and electron microscopic techniques. Taurine-like immunoreactivity was most dense and most prominent in laminae I and II of the dorsal horn. A moderate amount of immunoreactivity was also present in laminae VIII and IX and X while the remaining laminae were only lightly stained. In laminae I and II taurine-like immunostaining was evident within neuronal cell bodies, dendrites, myelinated and unmyelinated axons, axon terminals, and astrocytes and their processes. Cell counts of these two laminae indicated that approximately 30% of neuronal perikarya at the C2 level, 52% of neuronal perikarya at the T6 level, and 18% of neuronal perikarya at the L2 level of the cord exhibited taurine-like immunoreactivity. With preembedding diaminobenzidine staining, approximately 20% of the axons examined in laminae I and II were found to be immunoreactive for taurine. Using postembedding immunogold staining in combination with quantitative procedures, the highest densities of gold particles were found in axon terminals containing pleomorphic vesicles and forming symmetrical synapses (36.8 particles/micron2), in a subpopulation of myelinated axons (34.2 particles/micron2), in a subpopulation of neuronal dendrites (32.6 particles/micron2), and in capillary endothelial cells (39.8 particles/micron2). Moderate labeling occurred in astrocytes (20.9 particles/micron2) and neuronal perikarya (18.7 particles/micron2). The localization of taurine to presumptive inhibitory axon terminals provides anatomical support for the hypothesis that taurine may serve an inhibitory neurotransmitter role in the superficial dorsal horn of the spinal cord. On the other hand, its localization to astrocytes and endothelial cells within both the dorsal ventral horns implies that it serves other nonneuronal functions as well. 相似文献
997.
Ruth Dailey Grainger Clifford Levin Lois Allen-Byrd Ronald M. Doctor Howard Lee 《Journal of traumatic stress》1997,10(4):665-671
Controlled studies of treatments effective with victims of natural disasters are almost nonexistent. This is a small study conducted under difficult conditions to test the effectiveness of Eye Movement Desensitization and Reprocessing (EMDR) in treating trauma related reactions following Hurricane Andrew. The results were positive in that EMDR produced significant improvement over wail list controls in perceived posttraumatic avoidance behaviors and thoughts as measured by changes in the Impact of Event Scale and significant improvement in subjective aversive reactions to representative experiences of the hurricane. These results suggest and support other studies that EMDR can be an effective therapeutic intervention for trauma reactions. 相似文献
998.
999.
Ceftriaxone-associated gallbladder sludge. Identification of calcium-ceftriaxone salt as a major component of gallbladder precipitate 总被引:5,自引:0,他引:5
Ceftriaxone, a third-generation cephalosporin, is partially excreted into bile. With its clinical use, the formation of gallbladder sludge detected by ultrasonography has been reported. Four surgical specimens were examined and no gallstones were found. Instead, fine precipitates of 20-250 microns were present. Microscopically, there was a small number of cholesterol monohydrate crystals and bilirubin granules among an abundant amount of granular-crystalline material that was not morphologically cholesterol monohydrate crystals. The chemical composition of the precipitates (n = 4) was determined. There was a small amount of cholesterol (1.7% +/- 0.8%) and bilirubin (13.9% +/- 0.74%). The major component of the precipitate was a residue. On further analysis using thin-layer chromatography, high-performance liquid chromatography, and electron microprobe analysis, the residue was identified as a calcium salt of ceftriaxone. The residue also had identical crystal morphology and chromatographic elution profile as authentic calcium-ceftriaxone standards. It is concluded that ceftriaxone, after excretion and being concentrated in the gallbladder bile, can form a precipitate. The major constituent has been identified as a ceftriaxone-calcium salt. 相似文献
1000.
本文攀枝花市公共场所环境卫生质量进行了调查和分析。结果表明:空气中细菌总数超标82.7%,气湿超标71%,风速超标54.3%,噪声超标45.6%,CO2超标13.6%,CO超标9%。为改善公共场所卫生质量提出了建议。 相似文献