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The relationship between nucleolar and mitotic cycles has beendetermined after treatment of root apices of Zea mays with ethidiumbromide. In the meristematic regions of the stele the two cyclesare not much displaced in relation to each other except fora delay in the onset of the disorganization phase. A few nucleolipersist into metaphase and a few nuclei undergo an amitoticdivision. In the cap initials the drug greatly delays the onsetof disorganization of the nucleolus, which normally occurs beforeprophase in this region. It also delays the completion of reorganizationso that fully organized nucleoli are no longer available duringthe last half of telophase. In the quiescent centre the onsetof disorganization and the end of reorganization of the nucleoliare also delayed in relation to mitosis. There is no evidencefor a delay in the onset of reorganization in any region ofthe meristem. Some cells form multiple micronucleoli and this aberrant behaviouroccurs more often in the cap initials than elsewhere as doesamitotic division. 相似文献
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Adnan A Ezzat Ezzeldin M Ibrahim Madras A Raja Saif Al-Sobhi Assem Rostom Robert K Stuart 《Cancer immunology, immunotherapy : CII》1999,16(2):95-103
In the Kingdom of Saudi Arabia (KSA), breast cancer constitutes 18% of all cancers in Saudi women. Whilst locally advanced
breast cancer disease is unusual in Western countries, it constitutes more than 40% of all non-metastatic breast cancer in
KSA. The relative frequency of locally advanced disease among our breast cancer population and the lack of a uniform consensus
in the literature about its optimal management have prompted this retrospective analysis of the medical records of patients
with Stage III breast cancer patients seen at King Faisal Specialist Hospital and Research Center between 1981 and 1991. In
all, 315 patients were identified. Their median age ±SD was 46±11.6 years which is distinctly different from the 60–65 years
median age in industrial Western nations. Most patients were younger than 50 years (64%) and premenopausal (62%). Patients
were approximately equally divided between Stage III A and Stage III B Patients received multimodality treatment, including
surgery., adjuvant chemotherapy, tamoxifen, and adjuvant radiotherapy. Sixty-one patients were excluded from survival analysis
as they were considered lost to follow-up. Of the remaining 254 patients, 73 (29%) were alive and disease free, and 18 patients
(7%) were alive but, with evidence of the disease. The remaining 163 (64%) had died from breast cancer or its related complications.
Their median overall survival (OS) was 54 months, (95%, Cl, 27 to 121 months) and the median progression-free survival (PFS)
was 28.8 months (95% Cl, 14.2 to 113 months). Cox proportional hazard, model identified Stage III B and the number of positive
axillary lymph nodes as poor predictors of OS and PFS. Radiotherapy was the only adjuvant modality that affected survival
favourably. The prognosis of patients with Stage III disease remains poor despite the use of a multimodality approach. The
overall young age of our patients may have contributed to the poor outcome. Moreover, the adverse effect of Stage III B disease
(as compared with Stage III A) and axillary nodal status was evident. Whilst the favourable effect of radiotherapy on survival
was demonstrated, the lack of independent efficacy of other modalities (adjuvant chemotherapy and tamoxifen) or the apparent
deleterious effect of neoadjuvant chemotherapy should be addressed with discretion in such retrospective analysis. Optimal
management of patients with locally advanced breast cancer disease should be appraised in well designed, prospective, randomised
studies. 相似文献
86.
Persistent nuclear ribosomal DNA sequence polymorphism in the Amelanchier agamic complex (Rosaceae) 总被引:5,自引:0,他引:5
Campbell CS; Wojciechowski MF; Baldwin BG; Alice LA; Donoghue MJ 《Molecular biology and evolution》1997,14(1):81-90
Individual plants of several Amelanchier taxa contain many polymorphic
nucleotide sites in the internal transcribed spacers (ITS) of nuclear
ribosomal DNA (nrDNA). This polymorphism is unusual because it is not
recent in origin and thus has resisted homogenization by concerted
evolution. Amelanchier ITS sequence polymorphism is hypothesized to be the
result of gene flow between two major North American clades resolved by
phylogenetic analysis of ITS sequences. Western North American species plus
A. humilis and A. sanguinea of eastern North America form one clade (A),
and the remaining eastern North American Amelanchier make up clade B. Five
eastern North American taxa are polymorphic at many of the nucleotide sites
where clades A and B have diverged and are thought to be of hybrid origin,
with A. humilis or A. sanguinea as one parent and various members of clade
B as the other parent. Morphological evidence suggests that A. humilis is
one of the parents of one of the polymorphic taxa, a microspecies that we
refer to informally as A. "erecta." Sequences of 21 cloned copies of the
ITS1- 5.8S gene-ITS2 region from one A. "erecta" individual are identical
to A. humilis sequence or to the clade B consensus sequence, or they are
apparent recombinants of A. humilis and clade B ITS repeats. Amelanchier
"erecta" and another polymorphic taxon are suspected to be relatively old
because both grow several hundred kilometers beyond the range of one of
their parents. ITS sequence polymorphisms have apparently persisted in
these two taxa perhaps because of polyploidy and/or agamospermy (asexual
seed production), which are prevalent in the genus.
相似文献
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Anas M. Alazami Sarah M. Al-Qattan Eissa Faqeih Amal Alhashem Muneera Alshammari Fatema Alzahrani Mohammed S. Al-Dosari Nisha Patel Afaf Alsagheir Bassam Binabbas Hamad Alzaidan Abdulmonem Alsiddiky Nasser Alharbi Majid Alfadhel Amal Kentab Riza M. Daza Martin Kircher Jay Shendure Mais Hashem Saif Alshahrani Zuhair Rahbeeni Ola Khalifa Ranad Shaheen Fowzan S. Alkuraya 《Human genetics》2016,135(5):525-540