全文获取类型
收费全文 | 60187篇 |
免费 | 5248篇 |
国内免费 | 3563篇 |
专业分类
耳鼻咽喉 | 635篇 |
儿科学 | 727篇 |
妇产科学 | 586篇 |
基础医学 | 7287篇 |
口腔科学 | 939篇 |
临床医学 | 7097篇 |
内科学 | 9955篇 |
皮肤病学 | 787篇 |
神经病学 | 3367篇 |
特种医学 | 2747篇 |
外国民族医学 | 19篇 |
外科学 | 6381篇 |
综合类 | 8924篇 |
现状与发展 | 14篇 |
一般理论 | 11篇 |
预防医学 | 3773篇 |
眼科学 | 1397篇 |
药学 | 6368篇 |
52篇 | |
中国医学 | 2913篇 |
肿瘤学 | 5019篇 |
出版年
2024年 | 161篇 |
2023年 | 805篇 |
2022年 | 2068篇 |
2021年 | 2851篇 |
2020年 | 2069篇 |
2019年 | 1882篇 |
2018年 | 1967篇 |
2017年 | 1797篇 |
2016年 | 1974篇 |
2015年 | 2858篇 |
2014年 | 3368篇 |
2013年 | 3399篇 |
2012年 | 4871篇 |
2011年 | 5120篇 |
2010年 | 3671篇 |
2009年 | 2826篇 |
2008年 | 3448篇 |
2007年 | 3460篇 |
2006年 | 3137篇 |
2005年 | 3061篇 |
2004年 | 2208篇 |
2003年 | 2292篇 |
2002年 | 1918篇 |
2001年 | 1418篇 |
2000年 | 1090篇 |
1999年 | 1039篇 |
1998年 | 613篇 |
1997年 | 578篇 |
1996年 | 400篇 |
1995年 | 457篇 |
1994年 | 322篇 |
1993年 | 202篇 |
1992年 | 299篇 |
1991年 | 209篇 |
1990年 | 178篇 |
1989年 | 181篇 |
1988年 | 129篇 |
1987年 | 133篇 |
1986年 | 133篇 |
1985年 | 78篇 |
1984年 | 57篇 |
1983年 | 25篇 |
1982年 | 29篇 |
1981年 | 26篇 |
1980年 | 20篇 |
1979年 | 20篇 |
1978年 | 14篇 |
1973年 | 18篇 |
1972年 | 16篇 |
1969年 | 14篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
11.
Zhong Rui-kun钟瑞琨 Dong Yong-he董永和and Lu Dao-pei陆道培Institute of Hematology Beijing Medical University Beijing 《中华医学杂志(英文版)》1989,102(7):537-544
In order to understand the mechanism of immunosuppression caused by infusion of placental gamma globulin (PGG) in patients with renal allografts, rheumatoid arthritis, and graft – versus –host disease (GCHD) following bone marrow transplantation (BMT) ,we have examined the effect of PGG in vitro and in a model of the xenogeneic , local graft –ver- sus – host reaction (LGVHR) .PGG inhibited lymphocyte proliferation in mixed lymphocyte cultures (MLC) (P<0.005) and depressed interleukin -2 (IL-2) levels in such cultures at 72 hours (P<0.01) . In contrast phytohemagglutinin (PHA) –and pokeweed mitogen (PWM) –induced T and B lymphocyte blastogenesis was not affected by such PGG treatment .PGG treatment .PGG neither decreased the [3H] TdR pulse incorporation in unstimulated lymphocytes nor affected cell viability .Cell cycle analysis by flow cytometry showed that PGG reduced the percentage of cells in S and G2, M phases during the MLC, but did not alter cell cycling during PWM-stimulated proliferation .
An immunosuppressive effect of PGG on the LGCHR was tested in a model of intracutaneous transplantation of PGG –treat human lymphocytes into cyclophosphamide – immunosuppressed rats. Lymphoprep – separated human tonsillar lymphocytes were incubated with RPMI-1640 buffer containing:(1)PGG,4mg/ml,(2) human plasma albumin,4mg/ml,(3)mitomycin-C,25ug/ml, or (4) no additive. Cell of each preparation (3x107cells in 0.1ml) were injected intracutaneously into cyclophosphamide-treated male rats at separate abdominal locations. A fifth site received only the buffer solution. Five days after injection of cells ,each rat received [125 I]IUdR (10uCi) intraperitoneally and was killed after 5 hours. For each site of injection, the diameters of induration were measured and 125 I was counted . There was no difference between buffer – treated and a ibumin – treated groups either in the diameter of the area of induration (t=0.66;P>0.5)or in radioactive counts(t=0.22;P>0.05).In the PGG –treated group, the induration and radioactivity measurements were significantly less than in control groups (t=3.72 and P<0.1;t=2.62 and P<0.02,respectively ) Cytophilic antibodies in PGG were thought to inhibit an early phase of T cell activation, and not to be cytotoxicity .In the LGVHR, the immune response might be abrogated either by immuno- regulatory suppression of T cell function or by toxicity to the infused lymphoid cells. For some clinical purposes, immuno- modulating, human antibodies might be preferred to murine, monoclonal antibodies. 相似文献
12.
In-situ forming drug delivery systems are prepared by dissolving a drug and a biodegradable polymer (poly(D,L-lactide-co-glycolide), PLGA) in a biocompatible organic solvent (In-situ implant, ISI) or further emulsified into an external phase (oil or aqueous solution), resulting in oil-in-oil or oil-in-water emulsions (In-situ forming microparticles, ISM). The chemical stability of PLGA and the drug is a major concern. In this study, the stability of PLGA and leuprolide acetate in the in-situ forming systems and lyophilized sponges was investigated. The degradation of PLGA increased with increasing storage temperature and water content in the biocompatible solvents. A faster degradation occurred in polar protic solvents (2-pyrrolidone, PEG 400, triethyl citrate) than in polar aprotic solvents (N-methyl-2-pyrrolidone, DMSO, triacetin, ethyl acetate). The presence of leuprolide acetate significantly accelerated PLGA degradation, especially in solution state. PLGA was stable in oily suspensions at 4 degrees C and degraded only slightly faster than solid powder at 25 degrees C. No interaction between the oils and the PLGA was observed as indicated by an unchanged T(g) of approx. 47 degrees C. PLGA underwent a slight degradation at 4 degrees C after 150 days in water and saturated sodium chloride solution. The degradation was slower in saturated sodium chloride solution than in water at 25 degrees C. Residual acetic acid in lyophilized sponges facilitated the PLGA degradation in contrast to dioxane. Leuprolide acetate did not affect the PLGA stability negatively. However, lidocaine significantly enhanced the polymer degradation in the sponges. Finally, leuprolide acetate was chemically stable in the sponges, the oils and the polymer solutions in suspension state, but unstable (aggregation) when dissolved in the polymer solutions and stored at 25 degrees C and 40 degrees C. 相似文献
13.
Dong Hwee Kim Yoon Kyoo Kang Miriam Hwang Ho Sung Jo Ki Hoon Kim 《Clinical neurophysiology》2004,115(5):1021-1026
OBJECTIVE: To evaluate the usefulness of the TenElectrodes, a new stimulator for inching test, in the diagnosis and localization of ulnar neuropathy at the elbow (UNE). METHODS: Sixty-two ulnar nerves in 40 control subjects and 24 ulnar nerves in 23 patients with typical symptoms and signs of UNE were studied. The inching test of ulnar motor nerve using TenElectrodes was done along 8 cm across the elbow in the extended position. RESULTS: In the inching test of the control group, the mean segmental latency difference was 0.19+/-0.08 ms. Maximal latency difference over a 1 cm segment did not exceed 0.40 ms in any of the controls but exceeded 0.5 ms or more in all clinical UNE patients. In all UNE patients, the lesion sites were identified by the inching test using TenElectrodes: the retroepicondylar groove (54.2%), the humeroulnar arcade (29.2%), and dual compression (16.6%). CONCLUSIONS: TenElectrodes is a useful stimulator for the inching test in the diagnosis of UNE. The precise localization of compression was possible in all patients with UNE and the most common site was the retroepicondylar groove. 相似文献
14.
电脑比配色仪与比色板之间的相近性分析 总被引:1,自引:0,他引:1
目的:通过对比色记录的分析,比较Vita比色板、松风Vintage Halo比色板和电脑比配色仪之间的相近性和差异性。方法:随机抽取100名年龄在21~24岁的本地在校大学生,由男女两位测试者使用电脑比配色仪、Vita比色板和松风Vintage Halo比色板对被测试者的左上中切牙进行比色分析。结果:三种比色方法均以A色调最为集中,占总数的55%以上。其次是D色调占总数20%以上。男女测试者的选色在A、R、VR.系列中无明显差异。结论:电脑比配色仪、Vita比色板、松风Vintage Halo比色板均不能完全覆盖本地区青年天然中切牙的色度特征,只在A色调系列中重复率较高。 相似文献
15.
16.
管状膨体聚四氟乙烯用于组织工程支架材料的动物实验研究 总被引:6,自引:0,他引:6
目的:研究膨体聚四氟乙烯(ePTFE)植入动物体内后与机体的关系。方法:管状膨体聚四氟乙烯两端闭合,内充DMEM培养液,埋入家兔皮下,观察宿主生命情况,于术后1、2、4、6周取出标本,行大体及光镜下观察。结果:家兔在植入膨体聚四氟乙烯材料及DMEM培养液后存活情况良好,DMEM培养液在1周时即已完全无色透明;4周时膨体聚四氟乙烯与周围组织有粘连,6周时粘连紧密;光镜下观察,各时间点材料间隙均可见着色,1周时可见少量淋巴细胞浸润,无血管及组织细胞。材料内壁未见细胞附着。结论:植入膨体聚四氟乙烯材料及少量DMEM培养液对宿主动物存活无影响;管内外液体可相互交通,管状膨体聚四氟乙烯可作为组织工程化尿道的支架材料。 相似文献
17.
不同脑缺血和再灌流过程中大鼠脑组织NO含量的动态变化 总被引:12,自引:0,他引:12
采用线栓法制成大鼠大脑中动脉梗塞 ( MCAO)模型 ,依 Hb O2 - NO法测定持续性脑缺血和缺血 /再灌流脑组织内 NO含量的变化 ,以探讨不同脑缺血和再灌流过程中 NO的变化规律及其意义。结果 :缺血 3小时受损脑组织 NO水平即增高 ,再灌流后 NO逐步升高 ,而持续性缺血状态下 NO则表现降低后再升高的变化。虽然两组 NO在 7天时均有明显降低 ,但仍高于缺血前水平。认为持续性脑缺血和缺血 /再灌流情况下 NO的变化规律有所不同 ,与缺血脑组织的缺氧及产生 NO所需底物供应缺乏有关 ,且可能与脑组织的损害密切相关 相似文献
18.
Ming-I. Hsu Paul Kolm John Leete Ke Wen Dong Suheil Muasher Sergio Oehninger 《Journal of assisted reproduction and genetics》1998,15(8):496-503
Purpose:
Our purpose was to examine implantation of singleton pregnancies achieved following various assisted reproductive technologies (ARTs) through the appearance and rising titers of serum human chorionic gonadotropin (hCG) levels.
Methods:
A total of 114 singleton pregnancies resulting from in vitro fertilization and intrauterine insemination was analyzed. Patients were divided into five groups according to the type of ovarian stimulation protocol [gonadotropin stimulation with/without the use of gonadotropin-releasing hormone agonist (GnRHa), long protocol, or flare-up technique] and to the day of embryo transfer (day 2 or day 3 after oocyte retrieval). Serial serum hCG levels were measured between 10 and 25 days after fertilization and log-transformed. Linear regression analyses were performed and extrapolated to hCG = 10 mIU/ml (hCG
10
), which was used as an estimate of detectable implantation. The slopes of the regression lines were used to estimate the rising speed of hCG.
Results:
There were no significant differences in the days of hCG in maternal serum to reach 10 mIU/ml (implantation) or in the slopes of the regression lines for all five studied groups.
Conclusions:
The appearance of hCG in maternal serum was used to assess the time of clinically detectable implantation. Furthermore, because hCG production is a marker of trophoblastic activity, its serum doubling time was used as an indicator of embryo quality. Results showed that in various ART protocols with and without GnRHa, there were no significant differences in implantation time or embryo quality. Embryo development in early pregnancy follows a preprogrammed-timing schedule and depends mainly on the embryonic age of the health, successfully implanted conceptus. 相似文献
19.
Piotr Kozlowski Alastair M. Buchan Ursula I. Tuor Dong Xue Zhi-Gao Huang Karen E. Chaundy John K. Saunders 《Magnetic resonance in medicine》1997,37(3):346-354
31P, 1H and lactate spectroscopic imaging was used to evaluate the effects of hypothermia on focal cerebral ischemia produced by middle cerebral artery occlusion. The effects on high energy phosphate metabolism, pH, lactate and NAA were investigated in 24 spontaneously hypertensive rats subjected to either permanent or transient ischemia. Under either normothermic (37.5°C) or hypothermic (32°C) conditions, with permanent 6-h occlusion, there was little difference between groups in either the NMR measurements or the volume of infarction. In animals that underwent 3 h of ischemia followed by 12 h of reperfusion, the ischemic changes in lactate, pH, NAA, and high-energy phosphate returned toward control values, and there was a protective effect of hypothermia (infarct volume of 211 ± 26 and 40 ± 14 mm3 in normothermic and hypothermic groups, respectively). Thus, hypothermia did not ameliorate the changes in lactate, pH, NAA, or high energy phosphate levels occurring during ischemia, however, during reperfusion there was an improvement in both the recovery of these metabolites and pathological outcome in hypothermic compared with normothermic animals. 相似文献
20.
Qun Dong Sandra Kirley Bo Rueda Cher Zhao Lawrence Zukerberg Esther Oliva 《Modern pathology》2003,16(9):863-868
Cables, a cyclin-dependent kinase (cdk) interacting protein, has recently been identified and mapped to human chromosome 18q11. Cables appears to be primarily involved in cell cycle regulation and cell proliferation. Overexpression of Cables in Hela and other cell lines inhibits cell proliferation and tumor formation. We hypothesize that loss of Cables expression is associated with ovarian cancer. To test our hypothesis, we examined Cables expression in the four most common subtypes of ovarian carcinomas: serous, endometrioid, mucinous, and clear cell. In addition, mucinous and serous borderline tumors were also included. Loss of Cables expression was observed at high frequency in ovarian serous (11 of 14 cases, 79%) and endometrioid (5 of 10 cases, 50%) carcinomas. In contrast, strong Cables staining was detected in all clear cell carcinomas (10 cases) and mucinous tumors (5 carcinomas and 5 borderline tumors). The majority of serous borderline tumors (11 of 14 cases, 79%) showed positive Cables staining, with the rest showing focal loss of Cables expression. Furthermore, RT-PCR revealed the lack of Cables mRNA in a human ovarian cancer xenograft. No correlation was noted between loss of Cables and histologic grade, tumor stage, and survival. In conclusion, our results indicate that loss of Cables is common in ovarian serous and endometrioid carcinomas and imply that Cables may be involved in the pathogenesis of these two types of ovarian carcinomas. 相似文献