全文获取类型
收费全文 | 13921篇 |
免费 | 1243篇 |
国内免费 | 1043篇 |
专业分类
耳鼻咽喉 | 60篇 |
儿科学 | 222篇 |
妇产科学 | 151篇 |
基础医学 | 1643篇 |
口腔科学 | 201篇 |
临床医学 | 1740篇 |
内科学 | 2065篇 |
皮肤病学 | 168篇 |
神经病学 | 589篇 |
特种医学 | 671篇 |
外国民族医学 | 3篇 |
外科学 | 1306篇 |
综合类 | 2347篇 |
现状与发展 | 3篇 |
一般理论 | 2篇 |
预防医学 | 1021篇 |
眼科学 | 392篇 |
药学 | 1473篇 |
18篇 | |
中国医学 | 654篇 |
肿瘤学 | 1478篇 |
出版年
2024年 | 30篇 |
2023年 | 179篇 |
2022年 | 528篇 |
2021年 | 629篇 |
2020年 | 514篇 |
2019年 | 432篇 |
2018年 | 445篇 |
2017年 | 406篇 |
2016年 | 419篇 |
2015年 | 638篇 |
2014年 | 698篇 |
2013年 | 636篇 |
2012年 | 875篇 |
2011年 | 940篇 |
2010年 | 547篇 |
2009年 | 457篇 |
2008年 | 566篇 |
2007年 | 722篇 |
2006年 | 674篇 |
2005年 | 618篇 |
2004年 | 592篇 |
2003年 | 651篇 |
2002年 | 596篇 |
2001年 | 470篇 |
2000年 | 412篇 |
1999年 | 362篇 |
1998年 | 264篇 |
1997年 | 281篇 |
1996年 | 222篇 |
1995年 | 226篇 |
1994年 | 183篇 |
1993年 | 133篇 |
1992年 | 125篇 |
1991年 | 98篇 |
1990年 | 70篇 |
1989年 | 94篇 |
1988年 | 83篇 |
1987年 | 85篇 |
1986年 | 54篇 |
1985年 | 58篇 |
1984年 | 37篇 |
1983年 | 35篇 |
1982年 | 27篇 |
1981年 | 26篇 |
1980年 | 30篇 |
1979年 | 6篇 |
1978年 | 8篇 |
1977年 | 10篇 |
1976年 | 4篇 |
1975年 | 6篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
11.
目的 为了解高危新生儿脑干及听觉功能障碍情况.方法 于1995年8月~1996年1月对128例高危新生儿进行脑干听觉诱发电位(Anditory Brainstem Responses—ABR)测定.结果 急性期高危新生儿ABR异常率为51.4%,其中高胆红素血症,低体重儿,窒息和丁胺卡那霉素应用组ABR异常率分别为61.1%、66.7%、53.8%和 2.8%.血清胆红素(Sb)值>290.7μmol/L和重度窒息儿ABR异常率明显高于Sb<290.7μmol/L和轻度窒息儿.早产儿和足月小样儿ABR异常率无明显差异.丁卡组对听阀的近期影响不大.结论 高危新生儿是脑干和听觉功能障碍的高危人群,应当密切随防和早期干预. 相似文献
12.
Kaufmann SJ; Sharif K; Sharma V; McVerry BA 《Human reproduction (Oxford, England)》1998,13(2):498-499
The patient was diagnosed in childhood as having severe congenital
neutropenia and had recurrent admissions with severe infections. In 1987,
prior to getting married, she was sterilized. She continued to require i.v.
antibiotics when she contracted a severe infection. On one occasion, she
was treated with growth colony stimulating factor (G- CSF). Her increased
neutrophil count was sustained following this treatment. In June 1993, she
wished to start a family and underwent in- vitro fertilization (IVF)
treatment. G-CSF was given prior to oocyte retrieval. She conceived on her
first cycle and an ultrasound scan revealed a singleton pregnancy.
Throughout the course of the pregnancy, her white cell count was monitored
closely and remained at <1.0x10(9)/l. The pregnancy progressed
uneventfully and at 37 weeks gestation she was admitted for G-CSF
injections. At 38 weeks she was delivered of a boy weighing 3350 g, by
elective Caesarean section. His white cell count was normal. This is the
first case of G-CSF being used before conception and during pregnancy in a
patient with congenital neutropenia. It shows that advances in cytokine
therapy and close interdisciplinary liaison can lead to a successful
outcome and help patients, who would otherwise remain childless, to achieve
a family.
相似文献
13.
Silber SJ; Nagy Z; Devroey P; Tournaye H; Van Steirteghem AC 《Human reproduction (Oxford, England)》1997,12(11):2422-2428
The aim of the study was to determine whether a prior diagnostic testicle
biopsy can predict success or failure of testicular sperm extraction (TESE)
with intracytoplasmic sperm injection (ICSI) in patients with
non-obstructive azoospermia caused by testicular failure, and what is the
minimum threshold of sperm production in the testis which must be surpassed
for spermatozoa to reach the ejaculate. Forty- five patients with
non-obstructive azoospermia caused by testicular failure underwent
diagnostic testicle biopsy prior to a planned future TESE-ICSI procedure.
The diagnostic testicle biopsy was analysed quantitatively, and correlated
with the quantitative findings of spermatogenesis in patients with normal
spermatogenesis, as well as with the results of subsequent attempts at
TESE-ICSI. Men with non- obstructive azoospermia caused by germinal failure
had a mean of 0-6 mature spermatids/seminiferous tubule seen on a
diagnostic testicle biopsy, compared to 17-35 mature spermatids/tubule in
men with normal spermatogenesis and obstructive azoospermia. These findings
were the same for all types of testicular failure whether Sertoli cell
only, maturation arrest, cryptorchidism, or post-chemotherapy azoospermia.
Twenty-two of 26 men with mature spermatids found in the prior testis
biopsy had successful retrieval of spermatozoa for ICSI, 12 of their
partners became pregnant, and are either ongoing or delivered. The study
suggests that 4-6 mature spermatids/tubule must be present in the testis
biopsy for any spermatozoa to reach the ejaculate. More than half of
azoospermic patients with germinal failure have minute foci of
spermatogenesis which are insufficient to produce spermatozoa in the
ejaculate. Prior diagnostic testicle biopsy analysed quantitatively (for
the presence of mature spermatids) can predict subsequent success or
failure with TESE-ICSI. Incomplete testicular failure may involve a sparse
multi-focal distribution of spermatogenesis throughout the entire testicle,
rather than a regional distribution. Therefore, it is possible that massive
testicular sampling from many different regions of the testes may not be
necessary for successful TESE-ICSI.
相似文献
14.
β-Lactoglobulin was isolated from infant formulae that were ultra high temperature (UHT) -treated, sterilized or spray-dried. The effect of the isolated β-lactoglobulin on SfaII-fimbriae-mediated adhesion of Escherichia coli to human ileostomy glycoproteins was studied in vitro. β-Lactoglobulin isolated from sterilized formulae was found to perform significantly less well than preparations from spray-dried formulae (p = 0:05). Great heterogeneity was observed in the adhesion inhibitory capacity of β-lactoglobulin isolated from UHT-treated formulae. Therefore, no significant difference was observed between UHT-treated and sterilized formulae or spray-dried formulae (p < 0:10). It can be hypothesized that β-lactoglobulin from spray-dried and some UHT-treated infant formulae may affect the colonization of mucous membranes by E. coli strains causing neonatal septicaemia and meningitis. 相似文献
15.
16.
17.
J L Shao 《中华口腔医学杂志》1992,27(3):140-2, 189
In this paper, 220 children ranging from age 11 to 15 were selected. Each of them received a cephalometric roentgenographic examination. 153 cephalometric items from 13 types of methods which had been widely in use were studied through statistic analysis. By means of "t" test, several items which expressed little difference between the normal occlusion and the malocclusion were eliminated. By using of the cluster analysis we selected one item to represent the items which were with similar effect. Finally, 17 cephalometric items were pick out to provide references for clinical work. 相似文献
18.
Leukotriene B4 Receptor (BLT-1) Modulates Neutrophil Influx into the Peritoneum but Not the Lung and Liver during Surgically Induced Bacterial Peritonitis in Mice 下载免费PDF全文
Melanie J. Scott William G. Cheadle J. Jason Hoth James C. Peyton Krishnaprasad Subbarao Wen-Hai Shao Bodduluri Haribabu 《Clinical and Vaccine Immunology : CVI》2004,11(5):936-941
Leukotriene B4 (LTB4) is a rapidly synthesized, early neutrophil chemoattractant that signals via its cell surface receptor, BLT-1, to attract and activate neutrophils during peritonitis. BLT-1-deficient (BLT-1−/−) mice were used to determine the effects of LTB4 on neutrophil migration and activation, bacterial levels, and survival after cecal ligation and puncture (CLP). Male BLT-1−/− or wild-type (WT) BALB/c mice underwent CLP. Tissues were harvested for determination of levels of bacteria, myeloperoxidase (MPO), LTB4, macrophage inflammatory protein 2 (MIP-2), and neutrophil (polymorphonuclear leukocyte [PMN]) numbers at 4 and 18 h after CLP. PMN activation was determined by an assessment of phagocytosis ability and CD11b expression. Survival was also determined. BLT-1−/− mice had decreased numbers of PMNs in the peritoneum at both 4 and 18 h after CLP but increased numbers of PMNs in the blood at 18 h compared with WT mice. Liver and lung MPO levels were significantly higher in BLT-1−/− mice at both 4 and 18 h after CLP, with increased bacterial levels in the blood, the liver, and peritoneal fluid at 4 h. Bacterial levels remained higher in peritoneal fluid at 18 h, but blood and liver bacterial levels at 18 h were not different from levels at 4 h. PMN phagocytosis and CD11b levels were decreased in BLT-1−/− mice. LTB4 levels were similar between the groups before and after CLP, but MIP-2 levels were decreased both locally and systemically in BLT-1−/− mice. Survival was significantly improved in BLT-1−/− mice (71%) compared with WT mice (14%) at 48 h post-CLP. Thus, LTB4 modulates neutrophil migration into the mouse peritoneum, but not the lung or liver, after CLP. Despite higher bacterial and PMN levels at remote sites, there was increased survival in BLT-1−/− mice compared to WT mice. Decreased PMN activation may result in less remote organ dysfunction and improved survival. 相似文献
19.
以~3H地塞米松(Dex)为特异性配基,以一点分析法测得大白鼠腹腔中性粒细胞(PMNs)的糖皮质激素受体(GCR)位点数为5270±216/个PMN(n=18,X±SE下同);体外实验,PMNs直接与山莨菪碱(654-23×10~(-5)M)温育,对GCR无明显影响,测得位点数为4896±360/个PMNs(n=20,P>0.4);体内实验表明,给大鼠肌肉注射654-2(10mg/kg)每日两次共二天,则GCR位点数降至2740±101/个PMNs(n=18,P<0.001)。此时还测得血浆皮质酮含量明显增高(P<0.01)。提示654-2对GCR的影响可能与增加皮质激素所致的“降调节”有关。 相似文献
20.
Cholinergic neurotransmission plays a role in regulation of respiratory pattern. Nicotine from cigarette smoke affects respiration and is a risk factor for sudden infant death syndrome (SIDS) and sleep-disordered breathing. The cellular and synaptic mechanisms underlying this regulation are not understood. Using a medullary slice preparation from neonatal rat that contains the preB?tzinger Complex (preB?tC), the hypothesized site for respiratory rhythm generation, and generates respiratory-related rhythm in vitro, we examined the effects of nicotine on excitatory neurotransmission affecting inspiratory neurons in preB?tC and on the respiratory-related motor activity from hypoglossal nerve (XIIn). Microinjection of nicotine into preB?tC increased respiratory frequency and decreased the amplitude of inspiratory bursts, whereas when injected into XII nucleus induced a tonic activity and an increase in amplitude but not in frequency of inspiratory bursts from XIIn. Bath application of nicotine (0.2--0.5 microM, approximately the arterial blood nicotine concentration immediately after smoking a cigarette) increased respiratory frequency up to 280% of control in a concentration-dependent manner. Nicotine decreased the amplitude to 82% and increased the duration to 124% of XIIn inspiratory bursts. In voltage-clamped preB?tC inspiratory neurons (including neurons with pacemaker properties), nicotine induced a tonic inward current of -19.4 +/- 13.4 pA associated with an increase in baseline noise. Spontaneous excitatory postsynaptic currents (sEPSCs) present during the expiratory period increased in frequency to 176% and in amplitude to 117% of control values; the phasic inspiratory drive inward currents decreased in amplitude to 66% and in duration to 89% of control values. The effects of nicotine were blocked by mecamylamine (Meca). The inspiratory drive current and sEPSCs were completely eliminated by 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX) in the presence or absence of nicotine. In the presence of tetrodotoxin (TTX), low concentrations of nicotine did not induce any tonic current or any increase in baseline noise, nor affect the input resistance in inspiratory neurons. In this study, we demonstrated that nicotine increased respiratory frequency and regulated respiratory pattern by modulating the excitatory neurotransmission in preB?tC. Activation of nicotinic acetylcholine receptors (nAChRs) enhanced the tonic excitatory synaptic input to inspiratory neurons including pacemaker neurons and at the same time, inhibited the phasic excitatory coupling between these neurons. These mechanisms may account for the cholinergic regulation of respiratory frequency and pattern. 相似文献