全文获取类型
收费全文 | 263601篇 |
免费 | 22659篇 |
国内免费 | 16062篇 |
专业分类
耳鼻咽喉 | 2485篇 |
儿科学 | 3294篇 |
妇产科学 | 5044篇 |
基础医学 | 30205篇 |
口腔科学 | 4616篇 |
临床医学 | 33438篇 |
内科学 | 42168篇 |
皮肤病学 | 3027篇 |
神经病学 | 14483篇 |
特种医学 | 9299篇 |
外国民族医学 | 99篇 |
外科学 | 28725篇 |
综合类 | 39400篇 |
现状与发展 | 52篇 |
一般理论 | 46篇 |
预防医学 | 17157篇 |
眼科学 | 7003篇 |
药学 | 26746篇 |
194篇 | |
中国医学 | 12723篇 |
肿瘤学 | 22118篇 |
出版年
2024年 | 823篇 |
2023年 | 3822篇 |
2022年 | 9486篇 |
2021年 | 12490篇 |
2020年 | 9288篇 |
2019年 | 8252篇 |
2018年 | 8632篇 |
2017年 | 7694篇 |
2016年 | 7227篇 |
2015年 | 11055篇 |
2014年 | 13906篇 |
2013年 | 13162篇 |
2012年 | 19306篇 |
2011年 | 21017篇 |
2010年 | 13208篇 |
2009年 | 10540篇 |
2008年 | 14014篇 |
2007年 | 14064篇 |
2006年 | 13465篇 |
2005年 | 13451篇 |
2004年 | 9428篇 |
2003年 | 8546篇 |
2002年 | 7535篇 |
2001年 | 6719篇 |
2000年 | 6563篇 |
1999年 | 6772篇 |
1998年 | 3826篇 |
1997年 | 3840篇 |
1996年 | 2940篇 |
1995年 | 2713篇 |
1994年 | 2341篇 |
1993年 | 1547篇 |
1992年 | 2351篇 |
1991年 | 2051篇 |
1990年 | 1706篇 |
1989年 | 1484篇 |
1988年 | 1298篇 |
1987年 | 1202篇 |
1986年 | 969篇 |
1985年 | 766篇 |
1984年 | 495篇 |
1983年 | 386篇 |
1982年 | 230篇 |
1981年 | 204篇 |
1980年 | 194篇 |
1979年 | 245篇 |
1978年 | 141篇 |
1977年 | 112篇 |
1976年 | 97篇 |
1974年 | 116篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
The survival rate and elastic properties of the anterior abdominal skin flap in Sprague-Dawley rats were studied in three groups of animals. In group 1 where the flaps were supplied by a normal artery, arterial flaps (1A) had better survival rate and elastic properties than venous flaps (1B). In group 2, where the flaps were supplied by an artery with diminished perfusion pressure, the arterial flaps (2A) still had slightly better results than venous flaps (2B). However, in group 3 where the flaps were supplied by a vein, venous flaps (3B) had better results than arterial flaps (3A). 相似文献
102.
Macrobrachium rosenbergii that had been exposed individually for 24 h to 0 (control), 2, 5, 10 mg/L nitrite-N (nitrite as nitrogen) at 4.3 and 7.7
pH levels were examined for hemolymph nitrite-N, oxyhemocyanin, protein, acid–base balance, ion concentrations, and ammonia-N
(ammonia as nitrogen) excretion. Hemolymph oxyhemocyanin, protein, pH, HCO3
− , TCO2, osmolality, and ion concentrations were inversely related to ambient nitrite-N concentration and were lower at pH 4.3. However,
hemolymph nitrite-N, PO2 and PCO2 levels, and ammonia-N excretion were directly related to ambient nitrite-N, and were higher at pH 4.3. Ambient nitrite-N
and pH level interacted to cause changes in hemolymph nitrite-N, oxyhemocyanin, protein, PO2, and pH levels. It is concluded that for M. rosenbergii following nitrite exposure, the incorporated nitrite causes a decrease of pH and an increase of PO2 in the hemolymph where it reduces oxyhemocyanin level; disturbs nitrogen excretion, ion regulation, and respiratory gas exchange;
and may lead to a decrease of oxygen-carrying capacity, which are affected more at low pH.
Received: 31 August 1996/Accepted: 9 July 1997 相似文献
103.
α-L-岩藻糖苷酶测定的临床应用 总被引:1,自引:0,他引:1
研究结果表明AFU测定对肝癌的诊断具有较高的敏感性和特异性,其价值优于AFP,两项指标联合检测可提高阳性检出率。动态监测有利于肝癌的早期诊断、鉴别诊断,并可作为转移、复发的指标,也可用于白血病及卵巢癌的诊断。 相似文献
104.
Fluorescence polarization immunoassay and HPLC assays compared for measuring monoethylglycinexylidide in liver-transplant patients. 总被引:3,自引:0,他引:3
We compared fluorescence polarization immunoassay (FPIA, x) and HPLC (y) for measuring monoethylglycinexylidide (MEGX) concentrations in 119 serum samples from 61 liver-transplant donors and recipients. The correlation between the two methods was y = 1.48 micrograms/L + 0.8x (r = 0.89). The bias (mean difference) was 12 micrograms/L (0.055 mumol/L) through the MEGX concentration range measured (0-250 micrograms/L, 0-1.136 mumol/L). We observed a major difference between the two methods in samples from four recipients and one donor. Cross-reactivity in FPIA with lignocaine and two of its metabolites (glycinexylidide and 2,6-xylidine) was < 3%. Samples with high bilirubin concentrations (> 200 mumol/L) required dilution before assay of MEGX by FPIA. Although there was an increase in apparent MEGX concentrations in some samples with increased bilirubin concentrations, the relationship was not constant. Increased plasma concentrations of cholesterol and triglyceride resulted in relatively small increases in apparent MEGX concentrations. 相似文献
105.
Tetraethylammonium (TEA) effects on K currents were examined on either side of the membrane of hippocampal CA1 neurons by means of whole-cell voltage-clamp recording and intracellular perfusion. Recording media contained ion channel blockers to allow the selective activation of voltage-dependent K currents which consisted of a rapidly decaying component (A-current) and a delayed component. Voltage protocols were applied to separate the A-current from the delayed component. Results show that 10 mM extracellular TEA suppressed 50 +/- 11% (S.D., n = 4) of the delayed current at different levels of depolarization but had little effect on the A-current. In contrast 10 mM TEA applied by intracellular perfusion suppressed the A-current by 42 +/- 10% (S.D., n = 4) in addition to inhibiting the delayed currently 55 +/- 15% (S.D., n = 4). Both the intracellular and extracellular actions of TEA on K currents showed no voltage- nor time-dependency. The results suggest that voltage-dependent transient current (A-current) is mediated through a separate group of ionic channels distinct from those that sustained the delayed current. Furthermore, the asymmetrical effects of intracellular and extracellular TEA on the transient current are similar to those described for the A-current in molluscan neurons. This observation supports the notion that the structure of the ion channel mediating the A-current is closely conserved across different species. 相似文献
106.
川芎嗪对脑外伤患者血栓素、前列腺环素及颅内压的影响 总被引:6,自引:0,他引:6
28例重度脑外伤患者分为川药嗪治疗组和一般治疗对照组,两组病人均于用药前和用药后3小时测定血浆和脑室内脑脊液(VCSF)中血栓素代谢产物(TXB_2)前列腺环素代谢产物6—酮—PGF_(la)(6KP)和颅内压。结果表明:两组治疗前血浆、VCSF中TXB_2及T/K均明显高于正常献血员对照组,川芎嗪能降低脑外伤患者血浆、VCSF中TXB_2及T/K值,对颅内压则无明显影响。提示川芎嗪能抑制脑外伤对血小板的激活、纠正循环血中TXA_2—PGI_2平衡失调,从而改善脑微循环。 相似文献
107.
本文通过对38例经手术证实为异位妊娠患者手术前所测血清β-HCG与正常宫内妊娠(早期)血清β-HCG动态变化进行回顾性分析,探讨异位妊娠血清β-HCG动态变化特点,并比较17例异位妊娠的腹腔内出血β-HCG与静脉血的β-HCG之间关系。结果表明异位妊娠血清β-HCG明显低于同期正常宫内妊娠,有极显著性差异(P<0.01);且其动态变化呈单峰曲线而正常同期妊娠仍持续上升。腹腔内出血β-HCG明显高于静脉血;这两种特点对早期诊断异位妊娠有重要临床意义。 相似文献
108.
By a double-labeling method combining the retrograde tracing of horseradish peroxidase and the immunocytochemical technique, serotonin-like immunoreactive neurons in the midbrain periaqueductal gray (PAG) and nucleus raphe dorsalis (DR) of the rat were observed to send projection fibers to the nucleus parafascicularis of the thalamus bilaterally with an ipsilateral dominance. These serotonin-containing projecting neurons were observed mainly at the middle-caudal levels of the ventrolateral subdivision of the PAG and less at the middle-rostral levels of the DR. 相似文献
109.
A case of duodenojejunal intussusception secondary to a large hamartomatous polyp of Brunner's glands was reported in a 15-year-old girl. Despite a great preponderance of ileocolic intussusception in childhood, this is the first reported case of duodenojejunal intussusception occurring in that age group. The diagnosis was not made by clinical examination; complete duodenal obstruction was shown in upper gastrointestinal series and by endoscopy. The intussusception was reduced manually at laparotomy, and the polyp was excised. Pathological examination revealed a preponderance of normal-appearing Brunner's glands in the tumor, consistent with the diagnosis of Brunner's gland hamartoma. 相似文献
110.
We treated 56 consecutive acute segmental femoral shaft fractures with closed static locked nailing. 12 nails were dynamized after 6 (5-10) months due to slow fracture healing and 5 united after another 5 (3-8) months. The other 7 required cancellous bone grafting and all healed uneventfully 6 (5-8) months after grafting. Since dynamization did not promote healing in most of our cases we suggest early cancellous bone grafting in cases of delayed union. 相似文献