全文获取类型
收费全文 | 175792篇 |
免费 | 14232篇 |
国内免费 | 4997篇 |
专业分类
耳鼻咽喉 | 1110篇 |
儿科学 | 3156篇 |
妇产科学 | 1786篇 |
基础医学 | 27133篇 |
口腔科学 | 3433篇 |
临床医学 | 16981篇 |
内科学 | 26055篇 |
皮肤病学 | 2033篇 |
神经病学 | 7937篇 |
特种医学 | 3305篇 |
外国民族医学 | 24篇 |
外科学 | 13756篇 |
综合类 | 26100篇 |
现状与发展 | 13篇 |
一般理论 | 33篇 |
预防医学 | 16871篇 |
眼科学 | 4316篇 |
药学 | 17970篇 |
16篇 | |
中国医学 | 8252篇 |
肿瘤学 | 14741篇 |
出版年
2024年 | 210篇 |
2023年 | 2022篇 |
2022年 | 3011篇 |
2021年 | 5979篇 |
2020年 | 5453篇 |
2019年 | 5739篇 |
2018年 | 5688篇 |
2017年 | 5652篇 |
2016年 | 5862篇 |
2015年 | 5823篇 |
2014年 | 9199篇 |
2013年 | 11377篇 |
2012年 | 8670篇 |
2011年 | 10069篇 |
2010年 | 8699篇 |
2009年 | 8529篇 |
2008年 | 8468篇 |
2007年 | 9558篇 |
2006年 | 8849篇 |
2005年 | 8487篇 |
2004年 | 7444篇 |
2003年 | 6619篇 |
2002年 | 4931篇 |
2001年 | 4870篇 |
2000年 | 3965篇 |
1999年 | 3682篇 |
1998年 | 2656篇 |
1997年 | 2398篇 |
1996年 | 2427篇 |
1995年 | 2310篇 |
1994年 | 2055篇 |
1993年 | 1905篇 |
1992年 | 1645篇 |
1991年 | 1448篇 |
1990年 | 1189篇 |
1989年 | 1144篇 |
1988年 | 1031篇 |
1987年 | 784篇 |
1986年 | 579篇 |
1985年 | 641篇 |
1984年 | 659篇 |
1983年 | 398篇 |
1982年 | 491篇 |
1981年 | 417篇 |
1980年 | 361篇 |
1979年 | 301篇 |
1978年 | 247篇 |
1977年 | 202篇 |
1976年 | 237篇 |
1975年 | 149篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
992.
目的探讨腹腔镜辅助下行D2式胃底贲门癌根治术的临床效果。方法回顾性分析3年间行腹腔镜辅助下胃底贲门癌根治术22例患者的临床资料。全组均行腹腔镜辅助下近端胃大部切除术。结果无中转开腹,平均手术时间188(162~270)min。术中平均出血182(100~260)mL。淋巴结清扫18.6(10~32)枚。术后患者平均胃肠道功能恢复时间78(48~140)h。1例肿瘤侵犯食管下段的患者术后发生吻合口瘘,经留置空肠营养管、抗炎、充分引流等处理后4周痊愈。无手术死亡。全组术后随访1~37个月,平均9.2个月,无复发转移病例。结论腹腔镜辅助下行D2式胃底贲门癌根治术方法可行,效果好,具有视野清晰、创伤小、出血少、恢复快等优点。 相似文献
993.
Z. Peng Q. Liu Q. Wang E. Rector Y. Ma R. Warrington 《Clinical and experimental allergy》2007,37(7):1040-1048
BACKGROUND: Immunotherapy with anti-IgE antibodies for treatment of allergy is promising but a short half-life and extremely high cost limit its application. OBJECTIVE: We sought to develop IgE vaccines that induce longer-lasting auto-antibodies to neutralize self-IgE as an alternative therapy. METHODS: The vaccine was made by conjugating three synthetic peptides corresponding to human IgE receptor-binding sites to a carrier, hepatitis B surface antigen. To test the immunogenicity of the vaccine, rats were immunized with the vaccine or hepatitis B surface antigen as control. Serum IgG titres to human IgE and the IgE of other species were measured. The inhibition by rat antisera of the binding of human IgE to its receptor was assessed by ELISA, flow cytometry analysis, and passive cutaneous anaphylaxis (PCA), and its ability to recognize receptor-bound IgE was examined. The in vivo effect of the vaccine was evaluated in trichosanthin-sensitized mice and rats. In the preventative study, vaccination started before sensitization commenced, while in the treatment study, vaccination started after sensitization. Sensitized mice and rats receiving injections of the carrier served as controls. Trichosanthin-specific IgE was measured using PCA. RESULTS: Sera from vaccine-immunized rats contained high titre antibodies that reacted with soluble and plate-bound but not with receptor-bound human IgE; they also reacted with mouse, rat, and dog IgE. Furthermore, the sera inhibited the binding of human IgE to its receptor in a dose-dependent manner. In preventative and treatment studies, serum trichosanthin-specific IgE levels were significantly reduced in vaccinated groups compared with controls. CONCLUSION: Antibodies against self-IgE can be induced by IgE peptide-based vaccines, which are effective in preventing the increase of IgE and in down-regulating IgE in sensitized animals. 相似文献
994.
David G Norris 《Magnetic resonance in medicine》2007,58(4):643-649
This work describes a novel method for rapid acquisition with relaxation enhancement (RARE)/fast spin-echo (FSE) imaging that removes the constraint of compliance with the Carr-Purcell-Meiboom-Gill (CPMG) condition. In a multiecho sequence, echoes with either odd or even parities are acquired. The refocusing angles are chosen using a recursive algorithm, so that the signal amplitude satisfies a predetermined modulation function. In the examples given in this article an exponential decay to a plateau is used. At each echo the echo parity that gives the desired signal amplitude for the minimum refocusing angle is selected. It is further shown that in the presence of an initial magnetization having an arbitrary phase distribution, the complex conjugate of the signal of one echo parity has to be taken and its k-space coordinates reversed. T(2) (*)-weighted images are presented and initial applications to diffusion-weighted imaging (DWI) and functional imaging shown. 相似文献
995.
中鼻道及其周围结构的解剖学观测 总被引:1,自引:0,他引:1
目的 探讨临床上经上颌窦口进入上颌窦诊疗的途径。方法 在 40例成人尸体颅矢状切面上 ,对中鼻道、半月裂孔、上颌窦口及其周围结构进行解剖学观测及上颌窦口的探针插入试验。结果 中鼻道、半月裂孔的长度分别为5 6.3 6± 2 .5 8mm、2 1.46± 1.79mm ;40例中 ,2 8侧 (70 .0 0 % )的上颌窦口位于半月裂孔的中 1/3部 ;12侧 (3 0 .0 0 % )的上颌窦口位于半月裂孔的后 1/3部。上颌窦口的形态不一。上颌窦口的前后径为 3 .14± 0 .47mm。上颌窦口距鼻腔底部、鼻小柱的距离分别为 3 0 .41± 2 .85mm、49.5 2± 2 .3 7mm。鼻小柱到上颌窦口与到鼻腔基底面连线的夹角为 40 .2± 3 .7°。 3 7侧 (92 .5 0 % )的上颌窦口能用直径≤ 2 .5mm的探针穿过。结论 经上颌窦自然开口行上颌窦口穿刺是安全、简便和有效的一种诊治方法。 相似文献
996.
Rachel Anderson Lynell Clancy Neil Flynn Alex Kral Ricky Bluthenthal 《The International journal on drug policy》2003,14(5-6):461
An important operational aspect of Syringe Exchange Programmes (SEPs) is the venue of service delivery. This report describes the programmatic features of the Sacramento Area Needle Exchange (SANE), an illegal SEP operating in California, USA. SANE utilises “satellite exchangers” to distribute the bulk of its syringes and HIV risk reduction supplies. Advantages of relying primarily on Designated Exchangers (DE) for delivery of SEP services are that it: (1) allows for coverage of a large geographical area; (2) keeps operational cost low; (3) provides syringes to clients who may not want to or cannot use fixed site programmes; (4) limits the possibility of detection of programme personnel and clients by law enforcement. Limitations are that: (1) it is not as conducive as fixed sites to providing a wide range of ancillary services; (2) it may not be optimal for drug users who do not want to be reliant on other people for access to syringes; (3) those who receive services from a satellite exchanger may not derive as much counselling and referral services as direct exchangers. The lack of legal status, political support and adequate funding threatens the programme’s existence. 相似文献
997.
枸杞多糖对氧化损伤大鼠晶状体上皮细胞凋亡的调控 总被引:5,自引:1,他引:4
目的 :研究枸杞多糖 (lyciumbarbarumpolysaccha rides,LBP)对实验性晶状体氧化损伤所致晶状体上皮细胞(lensepithelialcell,LEC)凋亡的影响。方法 :复制大鼠晶状体LEC凋亡模型 ,将 2 4只透明晶状体随机分为 4组 ,空白组、H2 O2 组、白内停组、枸杞多糖组。枸杞多糖组加入终浓度为1g/L的枸杞多糖共同孵育 2 4h ,采用TUNEL法检测LEC凋亡率 ,用透射电子显微镜观察LEC超微结构改变。结果H2 O2 组LEC凋亡率 (92 .0± 2 .5 5 )显著高于空白组 (3.5± 1.84 ) ,(t=6 2 .97,P <0 .0 1) ;枸杞多糖组LEC凋亡率 (16 .6±8.11)与白内停组比较 ,差异有非常显著性 (t=15 .5 0 ,P <0 .0 1)。透射电镜观察 ,H2 O2 组胞浆明显浓缩 ,核内染色质凝聚或成块 ,枸杞多糖组多数LEC形态改变轻微 ,表现为胞浆基质密度轻度升高 ,部分线粒体水肿 ,细胞间间隙增宽。结论 :枸杞多糖可明显抑制LEC凋亡 ,从祖国医药中寻求防治白内障的有效药物具有广阔前景。 相似文献
998.
高度近视LASIK治疗中角膜瓣厚度的探讨 总被引:8,自引:0,他引:8
目的:探讨高度近视LASIK治疗中角膜瓣厚度问题。方法:142例(283眼)屈光度-9.00~-12.00 D的近视患者用日本NIDEK MK-2000全自动微型板层角膜切割刀切开角膜瓣,厚度71~184μm,激光切削方式一致。将角膜瓣厚度≤110μm分为Ⅰ组,72例(144眼);角膜瓣厚度>110μm分为Ⅱ组,70例(139眼)。对术前、术后屈光度、视力以 及剩余角膜基质床厚度进行比较。结果:术前平均角膜厚度:Ⅰ组为(531.76±30.28)μm(469~575μm),Ⅱ组为(550.66±24.45)μm(506~584μm),两者有明显差异(P<0.05)。术后剩余角膜基质床厚度:Ⅰ组为(333.01±3.30)μm(273~452μm),Ⅱ组为(309.71±31.41)μm(254~368μm),两者有明显差异(P<0.05)。术前屈光度两组分别为(-10.61±1.01)D及(-10.13±0.73)D,两组间无明显差异(P>0.05),术后7 d时分别为(+1.05±1.38)D及(+1.32±1.70)D,两组间也无明显差异(P>0.05),而术后3m Ⅰ组为(-0.13±0.94)D,Ⅱ组为(-1.06±0.96)D,两组有明显的差异(P<0.01)。术前、术后不论UCVA还是BCVA,两组无明显差异(P>0.05)。结论:治疗高度近视时70~110μm的角膜瓣的制作是合理的,并不影响术后视力,对防止术后屈光回退是有效的,对一个有经验的医生来说是可以很好完成的。 相似文献
999.
Morris R.S.; Paulson R.J.; Sauer M.V.; Lobo R.A. 《Human reproduction (Oxford, England)》1995,10(4):811-814
Ovarian hyperstimulation syndrome (OHSS) is a serious complicationof gonadotrophin usage but it is difficult to accurately predictits occurrence. Previous investigators have identified the combinationof high oestradiol concentrations and oocyte number as beingpredictive in 80% of cases. In this study we sought to identifythe incidence of severe OHSS in patients with high oestradiolconcentrations and large numbers of oocytes and to evaluatethe importance of pregnancy in the development of OHSS. Between1990 and 1993, we studied 139 cycles using two assisted reproductivetechniques [oocyte donor, n =72; in-vitro fertilization (IVF),n = 67] in which either oestradiol (>4000 pg/ml), oocytenumber (>25), or both were elevated. OHSS was diagnosed bystandard criteria. There were no cases of severe OHSS in theoocyte donor group and six in the IVF group. Among 10 patientswith oestradiol concentration >6000 pg/ml and >30 oocytes,only one had OHSS (10%). The relative risk of OHSS with pregnancywas 12 (confidence interval 2.1866.14). We conclude thatthe risk of OHSS even at high levels of stimulation is lowerthan previously believed. Secondly, donors have a very low riskof OHSS, probably because of the absence of pregnancy. As such,cryopreservation of all oocytes in IVF cycles is a reasonablealternative to cycle cancellation or use of adjunctive medication. 相似文献
1000.
Cholinergic therapy in dementia 总被引:4,自引:0,他引:4
P. J. Whitehouse 《Acta neurologica Scandinavica》1993,88(S149):42-45
After reviewing the evidence for cholinergic pathology in Alzheimer's disease and related disorders, this paper reviews strategies for treating dementia using cholinomimetic drugs. Special attention is paid to cholinesterase inhibitors, particularly tacrine, the drug recently approved by the FDA. New studies suggesting that muscarinic and nicotinic cholinergic receptor active drugs may be more effective will be reviewed. Brief mention will be made of strategies to slow the progression of Alzheimer's disease. 相似文献